Just to add to the confusion experienced in trying to troubleshoot this, some things that I tried (notably reverting to a backup of Windows, and changing the CMOS battery) did momentarily fix it, ie. Windows would successfully boot a few times, then it would soon be back to hanging after mup.sys. But disabling USB2 and keeping it disabled is the only thing that has continued to work for me.

Jim Runkey said:

When you enable something automatic you won't be aware of what is being applied/installed to a system. If you do a websearch you will see prooblems and problems being caused by automatic installations everywhere and caused by countless software problems...
It has nothing to do with being fast or slow in a computer.
When you choose to be notified of a critical update, you can review them, be aware of the problem and decide if you want it solved the way Microsoft tells you or not...
When you choose everything on automatic, you will get (sooner or later) a problem...
But i'm not against automatic updates...I just don't feel they are necessary...
In my case, a reliability update was there as a "critical update" and it has nothing to do with "critical anything" and it messed my system up...
Wanna bet many of these problems were caused by the same update being donne in automatic mode? Just count them up and tell me what you think...

Well, this problem seems well documented and I thank all those who helped me solve my "mup.sys" problem.

As, already pointed out, the problem seems related to both hardware and software. It seems that when something that is connected malfunctions or something in the hardware creates a software conflict, the safe mode loops. My solution, was to erase all the oem*.inf and oem*.pnf during the week before the problem occured. For me, the problem started when trying to hook up a PDA to sync with my Compaq (HP) Pesario V2000. This is right after I had synced a blackberry. I then proceeded to uninstall the blackberry program. With all the things I had been connecting to the USB ports (include wireless mouse, digital camera, digital video recorder, ipod, and several memory sticks, 2 different WiFi adaptors), I think the laptop just about had it and somewhere the software files confused the hardware (or visa versa).

I don't want to make it sound like it was that simple. Before I found this site, I agonized over the problem for days. These are the steps that worked for me:

1. Deleted the last few oem files (actually just renamed them in case I needed them)
2. Selected to repair from a bootable windows CD and did a chkdsk /p
3. Rebooted with bootable CD and selected to set up windows and chose the repair option
4. System stopped with error but when I rebooted (removed CD) it finished installing

I don't know which one of these steps was the true answer or whether any of them could be skipped, but I am happy for a positive result. Best of all, my previous programs and files were all in tact.

So, I hope this may help somebody as a bunch of you have helped me

I have same problem after I added 512 mb ram to my last free slot on my motherboard. After power on, my pc shows on the first screens correctly all 1,5 gb ram, but after that while logo windows xp pro sp1 shows (with moving blue indicator from left to right) it freezed. Imho that must be some software (driver ?) problem. Nothning else I changed. After that I tried Safe Mode and voila I get to win (but only in safe Mode). After that I suspected that problem may be that I have not sp2 so in safe mode I installed that. After that I booted normal with same reulst as I descripe above and went to save Mode. But Safe Mode way after sp2 did not work. So I gave up, removed 512 mb sdram and voila, WXP normally booted (Safe Mode i Normally), so I uninstalled sp2 and will have only 1 gb ram. This is my way of solution , but If anybody wil have any way to try something, I appreciate it.

btw: excuse my english

Hi all,

Reading this thread with interest. I have an XP SP2 machine that this morning hung with a blank blue screen. Once rebooted it now auto-resets right after the mup.sys messages. However trying a repair from the recovery CD doesn't work, it can't find the Hard Drive. So, has my drive gone west?

Ciao,
Andrew

If you have the ability, press F6 during boot, and get the windows boot menu. It may allow you to use the 'last good configuration'. That plus resetting the bios and pulling out all the USB cables on the box. I have a evga 680i motherboard with XP, and probably way to much stuff installed and it is getting unstable. That sequenced worked for me. And then reinstalling my motherboard drivers once I got some semblence of access to my machine again.

I'm considering rebuilding it with Linux, and run XP under Xen. The problem is I'm running four monitors and not sure how the Linux / XP combo will handle that.

If anyone else runs four monitors with Linux and XP in a VMWare or Xen session and thinks it works well, drop me a line at hardwareanalysis@oneunified.net

For unrelated meanderings:
http://www.oneunified.net/blog

This thread is amazingly still alive, so I'll post my 2 cents worth, even if its a repeat (i havent read all 35 pages, sorry).

I rebooted a computer that had been working fine for days (maybe weeks), and it hung as described by everyone else here. Google got me to this forum, and on page 1 I found the the message from GReddy in september of 2004. Windows was looking for a different keyboard.

I had recently added a USB KVM switch to my system, so GReddy's message seemed in my ballpark. With the computer still hung at the mup.sys line, I unplugged the KVM switch and plugged in a PS/2 keyboard. The system finished booting up right then. I plugged the KVM switch back in, removed the PS/2 keyboard (it took a minute to start working) and rebooted. The system rebooted fine this time.

Maybe some of you experiencing this problem will be as lucky as me to have this as your cause. It's sure easy to test.

My Intel 805 system, with the game hard drive. hung up on the mup.sys.
Even running in safe mode, the system wouldn't heal itself, and boot normally.

Instead, I:
a) copied the mup.sys onto a usb thumb drive from another computer
b) moved the thumb drive over to the affected system while in safe mode
c) copied the file onto the following location. c:\windows\system32\drivers\.
d) I then rebooted the system out of safe mode, and
e) things are working just fine.

I'll keep a copy of mup.sys named mup2.sys in the same drivers folder just in case the first one gets corrupted again. Then I'll only have to go into that folder with explorer, delete defective mup.sys file, and then delete the 2 from the mup2.sys file name, and then reboot. I'll also keep mup.sys on my thumb drive if somebody out in the field has the same problem.

Beto, I would be that what fixed your system had more to do with plugging and unplugging the USB thumb drive than it did with copying that file around. Did you compare the two files? Are they different?

Sorry, no, I didn't compare the two files. Also, I didn't have the thumb drive plugged in when the Mup.sys error cause the problems.
I think that the hard drive might have glitched where the mup.sys file was stored, but I'll not disect my system over several hours. Instead I'll play some more Battlefield 2142 with the time saved.

I don't think I could have corrected this mup.sys error without reading all the input from persons on this posting and website. . . Thanks, folks!

There's Good, and Then There's Lucky, and I'd Rather Be Lucky than Good.
This time I got Good and Lucky....

And Then There have Been Other Times . . .BZZT....Puff of Smoke and that Smell of Expensive Components Cooking . . . .

. . . Well . . . you get the idea...

Thanks again.....Beto

Hi. I have been having this problem for months but I just chalked it up to "minor inconvenience", but it has come to a head, so I researched what was causing it. I found this forum among other sites and long story short, disabled mup.sys, still had the problem, only with another file. disabled that, another file. etc etc I did this about 10 times for 10 files when I decided enough was enough. I backed up the important stuff on my HD and wiped it, restoring it with a baseline Ghost Image. Unfortunately, that didn't fix my problem. I then thought that it could be the work of a trojan or something, so Installed a fresh copy of windows onto my drive. Nope, still stalling at bootup. I replaced my 160 gig Western Digital with an 80 gig, and restored the ghost image onto that, but still the problem persists. I swapped IDE cables, problem persists. I am sure now that it is a motherboard issue, but I need to know if it is something that can be fixed. My BIOS are up to date as far as I know (I bought the mobo in 2006, the latest bios are from 2005, but I am going to flash them to make sure.) I am at the end of my rope, what could be causing this issue and how the hell do I fix it?

This might sound silly, and might be wrong, but try swapping out your keyboard and maybe even your mouse. Especially if they are USB, swap them for PS/2 models.

This is my second go-around with this problem--and I'm facing it again.

The first time I tried a lot of the basics: new hard drive, clean install, etc. None of that worked. I eventually found a thread (somewhere) that mentioned something about bad RAM. I put back my original HD with the last version installed, removed the suspect RAM module and that did the trick. All has been good for about four months--until now.

I've been using a number of USB devices, mainly Pocket PC devices. I've swapped these thing back and forth, only to find that one day, while my Toshiba Satellite was confused about an issue and froze, did the MUP.sys file come back to bite me.

To troubleshoot this issue, I went back to what saved me in the first place: swapping RAM. This time that did not do the trick. I've played around with various USB configurations. I even reseated the processor (that fixed a previous thermal problem). No dice.

Personally, I am not eager to replace my previous install of the OS with a new one. When I tried it before, it failed to work correctly and I was still stuck with the MUP.sys issue. So before I try it again, I wanted to ask a few questions in the hopes that one of these may lead to a resolution. The challenge is that I am not completely versed with the start-up protocols to know how to do what I'd like; thus the questions.

Here they are:

How can I reset BIOS to factory defaults?
Is there a temporary hardware memory stored in something akin to EPROM?
(If so, can this be flashed clean before the HD is accessed to read what should be there?)

My logic is that even after a clean install of the OS, if the MUP.sys file is still corrupt, then something must be causing bad data to be written to the file. Therefore the source of this bad data--a ROM-based temp file with various hardware configurations/components--should be the culprit. If this is the case, when you install a new OS, you are not wiping this file clean (or updating it with current information) and the new OS reads this hardware file only to get bad data looping back to the same problem.

Any suggestions or comments would be appreciated.

Same problem here at our client. We run the exact same Lenovo desktops all over the company. Today we get a call, user getting Windows freezing on MUP.SYS.

So using this forum here is what I have tried so far, trying to boot after each step to see if its resolved:

Restored BIOS Defaults

Disabled MUP with recovery disk

Replaced MUP.SYS with one on SP2 XP CD

Took out hard drive and put it in another identical Lenovo, brand new so new CMOS battery all new hardware etc, proves its not a hardware error

Tried booting with no USB keyboard or mouse installed

Tried safe mode

Tried Last Known Good

Tried to repair the Windows installation (not available on this install)
even after rebuilding the bootconfig / boot.ini, replaced the ntldr even and misc system files (did not attack registry)

This machine is configured like the other hundred we have, idential hardware, software, updates, and the user did not plug anything into it. Worked great for at least a few years.

At the end of my rope. Currently imaging a new machine and will copy over her documents but would like to know the answer to this one, I don't see what else it could be.

Here is how I fixed this two time.

Last year my wifes puter did this....it would freeze at mup.sys. I simply unplugged the wireless card and it rebooted. The card was dead.Problem solved.

Today it did almost the same thing....except it would boot to mup.sys and then reboot over and over. I had a new usb wirelss device so I knew it wasn't it. I unpluged it anyways....took out all card except the video card...no go. No matter what I did it would not boot.

I took the drive out of that computer and installed it as a slave on my computer. When my computer booted, it automatically did some system scans and found bad sectors. I guess it fixed them. I ran a virus check on the drive and then reinstalled it onto the other comptuer and it booted up just fine. It did run another system scan and foud the bad secors again but after that boot, it seams fine. I've rebooted it several times and each time it boots fast with no problems.

I suspect that I need to get a new drive SOON...as that one must be dieing. It's an old WD 40gb...so it's been a good one. All data is now backed up and I will buy a new drive for her ASAP.

Just though I would share my experience...please excuse the typos.

hmm, lot of confused people in regards to the mup.sys. Suppose if you read everything you'll know that file is not why its not booting (or maybe not hahah cuz mup.sys is wat its all but on almost every forum ive been too), but at least it'll point you in the right direction.

That being here.
support.microsoft.com/?id=885626

Often occurs after software installation or using windows automatic updates, in fact happen to me right after updating some security fixes on a fresh install. Researched for a few hours, did the same thing others did (tried replacing/disable mup.sys, using chkdsk, fixing boot sector and mbr) but this is it, stupid update.sys. Otherwise more likely you bios needs updating.

If you dont have ur cd, i found a copy of the xp recovery console but I dont wanna hotlink it, so go on google and type "recovery console iso." (its not the os, just the console)

Angel Robert said: Thanks for the suggestion, Robert. The KB article you point to is something folks suffering from boot hangs to consider, but the problem it addresses affects only a very narrow set of CPUs, and thus while it may help some users, it will not be the solution for everyone.

Many, many problems (both hardware- and software-related) end up giving users the "hangs at mup.sys during safe mode boot" signature. If there was a single solution, this thread would not be 35 pages long and still getting replies.

Thanks for adding another potential solution for users to consider.

mup.sys is not the problem in 99% of the cases of the so calledmup.sys failure. mup.sys just happens to be the last file to load before windows takes over. If windows can't take over it stalls and you get the above problem. Generally this is a hardware failure of some type and your troubleshooting should start at doing a barebones setup.

I've found that the HDD is usually the culprit. It is beginning to fail and is corrupting itself. People reload windows and all is well until the failing drive corrupts itself again. This continues till the drive fails completely.

Usually is the operative word above because it can also be another hardware item stopping windows from taking over. RAM can cause corruption on the boot drive as well and any failing hardware component such as a wireless or NIC card that has died can cause a windows load stall. That is why a barebones is a good place to start. This guide may help some folks with troubleshooting:

This is a little guide I made up for doing a barebones setup. It is a great troubleshooting tool that all of us need to use at one time or another. If you can see any changes that will improve this guide, or the procedure, then please post them as this is a work in progress.

BAREBONES SETUP

You are going to have to do a barebones setup and test each component. This will read a lot harder than it actually is. The initial procedure takes only around 10-15 minutes. The follow on troubleshooting may take a lot longer though. Also, please do not skip steps. Do everything in order and as listed or your troubleshooting will be flawed.

Caution: Please remember that turning a PC off does not mean there is no power going through it. Modern systems maintain a trickle of power to keep the standby functions running. You either have to turn off the switch on the Power Supply Unit (PSU) itself or unplug the system from the wall. Unplugging is best. If the green LED on the mobo is lighted you have power to the board. Make sure it is out before proceeding. Also, be aware of static. Make sure you wear an ESD strap or discharge yourself on a steel part of the case before touching anything inside.

First, unplug the PC from the wall and then push the power switch for a second to discharge any "leftover" electricity and then open up the case. Disconnect all the drives (floppy, CDROM, DVD etc.)from the motherboard (mobo) and also disconnect your Hard Drive(s) from the mobo. Do not leave the hard drives connected, the system will boot into BIOS just fine with no hard drive attached. Unplug the power from all those drives you disconnected from the mobo and remember to disconnect the front panel firewire and/or USB ports. If you have a PS2 keybard and mouse, use them instead of the USB models.

Next, remove all the RAM, except for one stick, from the mobo. Some mobos are very picky about where the RAM needs to be placed so make sure the one stick of RAM is in the correct slot as per your manual. On the A8N SLI Deluxe this slot is the third one (B1) as you move away from the CPU.

If you're SLI then remove the second video card. Remember to set the SLI Selector Card to single. Unplug the EZ plug molex from the board.

Now you are stripped down to a barebones system. The PSU, the mobo itself, 1 stick of RAM, the CPU/HSF and one video card. Reset your CMOS/BIOS while the system is stripped down, unplugged and open. You do this by removing the battery and then moving the jumper near the battery around. On the A8N SLI Deluxe there is a set of three pins, with two covered by a jumper, right next to the battery. After removing the battery, you move the jumper from pins 1&2 to pins 2&3 and let it set for a few seconds, then reset the jumper back to pins 1&2 and replace the battery. BIOS will be back to default settings after doing this.

Now, check that everything is seated correctly, RAM, video card and its power plug if applicable and the 3 pin CPU HSF power plug. Check that both 4 pin (P4 Power)and 24 pin power is connected and secure. Now plug the PSU back into the wall and turn it on. The green LED on the mobo should be lighted. If the LED is lighted then turn the PC on. Hopefully she boots right back into BIOS.

If you get back into BIOS you can start troubleshooting by turning the PC off, unplugging it and reconnecting peripherals one at a time. The idea here is to connect and reboot, until something hangs your system up. This, presumably, is the bad piece of gear. Start with the optical drive and floppy drive, then the hard drive with the OS on it and finally the second video card if applicable.

If you cant get into BIOS then you know it is either the PSU, the RAM, the CPU, the mobo itself or the video card. Change out each of these until you get into BIOS. I would start at the PSU as it is usually the guilty party in a situation like this and is also easy to change in and out (you are down to just 2 plugs, now, remember). Next up would be the video card and/or RAM and if still no luck then things get hard as you now have to consider either the CPU or the mobo.

Good luck and happy hunting.
MERC

mup.sys is a driver file the the NIC (Network card). I have noted that some think that this is a problem whith the next file that will load. I have tested that and by my results that is not the case. There is a Memory conflict between the NIC and some other device in the system. Use the Recovery console or the UBCD (link http://www.ultimatebootcd.com/) to boot the system and rename the mup.sys file to mup.sys.old (DO NOT DELETE THE FILE! or any other system files untill you know that windows dose not need it.). The file is located in windows\system32\drivers. (windows will boot with out this file but if you have a LAN (Local Aria Netwrok) you will not be able to browes it untill you rename the file back and reboot) After you rename the file reboot to local hard drive. once windows is up and running log in to all accouts the reboot and do it again. After you have rebooted at least 2 times (3 or 4 would be better) rename the mup.sys.old back to mup.sys and reboot one more time. if that fails then the HAL is mest up. you can rename name the mup.sys back to old and then do a repair install of windows.

My solution to this issue turned out to be hardware related. Both the onboard USB and LAN were causing the lock up. I found this out after testing the memory, the HD, reloading the O/S and many of the other suggestions listed. I disabled all onboard items in the Bios and loaded them one by one. I hope this helps someone else as this error is a pain!