I have been having this problem over the past two days and instead of reading the thousands of pages here, I figured I would just give my story and see if anybody has any idea how to help me.
I started my computer yesterday to find that it was telling me to choose either 1/3 kinds of safe mode, last known config, or to start normally. I have chose every single one and each end up showing me that Windows is loading just to reboot. I have tried a few different things and some were to unplug my mouse and to disable BIOs but in order to do that I would need to get in to safe mode. Safe mode isn't exactly working though.
I have no idea what to do, any info would be appreciated. Although a lot of this is sort of confusing because I don't exactly know a lot when it comes to computers and how to fix them.
Thanks for any help, it is appreciated!!

Hi Steph,
I see noone has replied, so here is some info!
You are probably in the Wrong Forum (to do this is often reguarded as rather impolite or sinful!) as you do not apparently have a 'hang at mup.sys' !!
You probably have a 'Blue Screen Of Death' error (which can cause an immediate reboot - so quickly that you do not have time to read the message on the blue screen!).
I remember that a while ago on this forum, some guy had the great idea of photographing the message with a digital camera, but he didn't say how many times he tried this before he got a readable picture.
There is a way to stop the reboot (& maybe read the message) but offhand I don't remember how! If noone else answers I may find time to look it up later - but look in other forums first for BSOD errors.

Nick Law

This is what fixed it for me.

I've had this problem on a system I bought second-hand a couple of weeks ago. It was working fine when I got it, but after a day it froze at the screen where the last file listed is mup.sys. I couldn't even get into Safe Mode or the Command Prompt, nor could I get the XP Setup to run to try a repair.

I'd foolishly convinced myself it was a software problem after reading most of what's been said here, but as I was about to give up I recalled what someone had mentioned ... I opened the case and noticed that the grey ribbon cables were kinked in places - they are of a rather brittle-looking type too. After straightening them out the PC started up! If it happens again I'll replace them.

There seem to be any number of things which can cause this problem - but I hope this will help someone else. It only takes a few minutes to check.

I have a similar problem (surprise, surprise).

Here's a little background:

I'm working on a laptop for an acquaintance. It has Windows XP Media Center Edition 2005 installed. I got a set of install discs (owner doesn't have them; he bought this as a used computer) and, to avoid ruining the laptop, I installed the OS on my own computer (which already has a copy of XP Pro (SP2) on it, so it's now a dual-boot system).

My computer has 4 SATA-II drives (160GB each) plugged into the motherboard's on-board nVidia RAID controller; the drives are arranged into a pair of striping arrays, 320GB each, which gives me two logical drives visible from Windows XP (C: and D. Since XP Pro is installed on C:, I installed MCE on D:.

As soon as the installation process was done, my computer started having problems booting into MCE. It didn't freeze, but it kept re-starting itself, and when I tried booting into safe mode . . . I think you see where this is going.

But it still boots into XP Pro without any problems.

For booting into MCE, I tried a number of solutions: disconnecting all USB devices, removing drives from my DVD burners, disconnecting the DVD burners, resetting the BIOS to "optimized defaults" (this broke my RAID, so I had to go back in and re-enable it just to use the computer), and disabling MUP via the repair console, all to no avail. I had already flashed the BIOS to the latest version provided by the manufacturer; I had to do that when I recently upgraded from a single-core CPU to a dual-core CPU.

Since XP Pro works just fine, I doubt I'm having hardware issues--it may simply be an incompatibility issue between MCE and my particular configuration. But I don't want to risk putting this on my "client's" laptop if it's going to break it, because I may not be able to fix it.

I am making a full backup of the laptop (by booting with an "Ultimate Boot Disc" with networking enabled so I have access to all the system files), but if I have to reformat and restore from backup, I'll still have to do a repair install from a potentially corrupted set of install discs which may not have all the necessary drivers. (They're available at Toshiba's web site, but it is something of a hassle.)

Laptop:
Toshiba Qosmio G25-AV513
(c|net review: http://reviews.cnet.com/Toshiba_Qosmio_G25_AV513/4505-3121_7-31413530.html)

My computer:
Gigabyte GA-K8N Ultra-SLI
AMD Athlon 3800+ 64-bit dual core
2GB RAM
Matrox Parhelia APVe 128MB

Does Windows MCE simply not like to play nice with computers that use SATA drives as the primary boot HDD? (I did load the nVidia SATA RAID drivers from a floppy drive as the installation process was beginning, of course.)

Thanks for all your help. After reading the postings I unplugged the keyboard and rebooted the computer. I received a message that the keyboard was missing so I plugged it in and hit F1. Once it started loading I quickly unplugged the keyboard and Windows XP started correctly. I can't doing anything but at least Windows XP is working. I've been wanting a new keyboard, now I get my wish.

We found this Compaq 1.0GHz 2001 in a dumpster with dead power supply and dead keyboard and a bad CD-ROM drive plus a good CD-RW (burner).
It had been upgraded to 20GB hard drive and 256MB RAM with Xp Pro SP2.
No XP CD. Booted okay with replacement Compaq power supply and a different keyboard, developed the boot problem with mup.sys in safe mode when we replaced the original CD-ROM drive.
Tried setting BIOS to defaults and changing RAM, then unplugged one CD-ROM drive and it booted. Plugged that one in and unplugged the other and it booted. With both it will not boot. Maybe our power supply is a bit weak? I never would have guessed to unplug a drive. (We also tried a different IDE cable as suggested, removed USB flash drive, but did not enable in BIOS IPCA, IOPAC, APIC or power management, and there is nothing in this minimal BIOS about cache).

So I appears to have nothing to do with any particular model of CD-ROM, just too many drives.

Thanks for the help.

Now i have this damn problem! Stupid service pack 2 and its stupid "unable to install" cause some bulls**t file error!
i have tryed chkdsk /p - ( and yes it did find errors)
i have tryed fixboot
rulled them out cause they both dont work
now im tryin the hands on, take the battery out for a few hours.

and now we wait.....

God Created s**t, Bll Gates made it Microsoft..
F**K Microsoft, just more crap to land on store shelves

Mup.sys is my problem too and it's very tricky.

I have a notebook Acer Aspire 3610. I'm using 2 HDD's, one is my private and one is for business stuff. On both I have WinXP Pro, and with my private I have no problem it's working just great, but on my second HDD I have the mup.sys thing.

I read almost all the forum, updated BIOS, exchanged files in the system32 and system32/drivers, even made a backup of the drive and put it on a different HDD, and it didn't help. I only didn't use the recovery console, because I don't have the administrator password for the business HDD. Perhaps there is any method I can get the pass or you have any idea what else I can do with the laptop?

My little suspicion is my DVD drive which sometimes is or isn't found duing the start. But on the other hand on my second HDD there is no problem and with or without the DVD drive it works just perfect. What may it be then?

Another one finally solved - all thanks to this short thread . What a mess this one has been.

For reference, I put the drive from an IBM T41 into a T40 and the symptoms were the same, so I didn't think it was BIOS related. I had a BSOD 0000006B error, but it wasn't always that, and various changes took place and the BSOD error message changed at least twice.

With similar problems to most of you, I tried the chkdsk /r and it found several errors, tried to fix them but couldn't resolve them all. Tried renaming agp440.sys and a BIOS reset to default and then, after some frigging around, managed to get the Windows Repair utility going, at first it wouldn't fire, but then after reading this thread and tinkering around I tried again and it fired up.

Half-way through it started complaining that it couldn't copy files from the CD-ROM so I pointed back at C:\i386 and it then displayed a svchosts error, which I ignored because XP seemed to continue the install.

Once finished, it rebooted then hung with a Windows splash screen and a "Please wait...". Finally did a hard reset and tried booting in Safe Mode, which it did. After two error messages (which I ignored) up came the logon screen. I logged on to Safe Mode and then shutdown the system.

I then started up again and logged on to normal Windows XP using the same password that I had before all of this utter b.s. started. Seeing my old desktop background again was most relieving. Got an MSN message and a windows activation note, other than that, it looked sufficiently stable to get my critical files off!

Perhaps it's time for a performance upgrade and a downgrade to Win98?

Guys, I also have had problems and it looks like it can be hardware or software related. In my case it was software.

About 2 weeks ago I installed a new printer (Epson R1800) and everything was going swimmingly until an application crash (Photoshop) caused the Blue Screen of Death followed by a swift reboot. Laptop started up again and I was working merrily away when after about 3 hours it went again. Hoping it was just 'bad luck' I ignored the signs and rebooted the machine. It went OK for a day or so then the crashes became more regular and random. Finally after installing a McAfee patch the machine went into continuous reboot and when I tried to start in safe mode it appeared to hang on Mup.sys.

After trawling throught the pages of posts I discovered that if I sat it out, the machine would eventually get past mup.sys which it did. I got to the XP login screen then BANG... it went again. The only way I could get any action was by restarting in safemode with command prompt.

When I got the DOS window up, my immediate thought was to backup all my work onto my USB drive which thankfully was still being recognised. I had a fair idea at this point my problems lay with software rather than hardware and I was thinking of a reformat and all the hassle that would bring. After reading through all the posts in this thread (which has all the answers but only if you bother your a$$ to read them) I knew that even a reformat may not cure my problems.

After backing up all my work and only getting one crash when I removed the USB drive, I rebooted with command prompt, used dos commands to get me to the windows directory where I ran explorer.exe which brought up the familiar windows explorer interface.

Logically I was thinking McAfee must have caused all the problems because it was after installing the latest update the machine went belly-up, however when I analysed the error logs and disocovered that one of the services that had been installed with the epson printer was causing all sorts of problems (Print to email or something similar).

Despite running for a couple of weeks problem free, some reason the epson software was now in real trouble (something must have got banjaxed when photoshop originally crashed).

I was able to open up control panel and remove the epson software, though the problematic 'email-print' thingymajig couldnt do a complete uninstall in safe mode. So I rebooted in normal mode and heypresto, she was alive. I went into control panel/add-remove programs and uninstalled the remaining epson software.

3 days later, she is running like an eskimo's nose.

The moral of this story is two-fold
1. Read all the posts in this thread, the answers are in there. People have taken the time to share their advice with you, make the effort.
2. Read ALL the posts

Thanks for your contribution, M L. I have a couple of questions, to better understand your troubleshooting process.

M L said: Was this just a hunch, or did you have any particular data to support this? (Just curious.)

This seems like an odd conclusion to me, since you had been having intermittent BSODs for some time before the McAfee update.

Can you elaborate a little on the "error logs" you analysed? Which logs were these?

Were you able to determine from the logs that the problems didn't start to appear until after the Photoshop crash? (I wonder if the Photoshop crash was just a symptom, not really a cause.)

Thanks again for your contribution,
Jim

M L said: Was this just a hunch, or did you have any particular data to support this? (Just curious.)

I first suspected the problem was software related after I got the laptop up and running in safe mode with the command prompt. I had unplugged every peripheral that wasnt necessary to get the machine up and running. I hadn't added any new hardware (apart from the printer which was powered down), all the ram was being recognised as was the processor, HD etc. The hardware appeared to be present and correct, so I then turned my attention to the software.

This seems like an odd conclusion to me, since you had been having intermittent BSODs for some time before the McAfee update.

Can you elaborate a little on the "error logs" you analysed? Which logs were these?

I had been experiencing intermittent problems but each time the machine would restart and work as normal. I didnt keep a note of how many times this happened previous (been pretty busy in work) but after I installed the McAfee update the machine wouldnt restart.

When I got it runinng in Dos mode with explorer I was able to check the System Information/software environment/windows error reporting logs which showed me a couple of serious errors all pointing to the Epson software.

Were you able to determine from the logs that the problems didn't start to appear until after the Photoshop crash? (I wonder if the Photoshop crash was just a symptom, not really a cause.)

I didnt check the logs prior to the Photoshop crash, I had no need to because the machine was working fine (thats typical!). It's only in retrospect that I recalled the machine started playing-up after the photoshop crash. I also cleared the logs down prior to the last crash to try and make it a bit easier to see what was going on therefore I did not look at the pre-photoshop crash logs! In fairness at the time of the photoshop crash I knew I was pushing the laptop to the max, and I knew that the epson software shared some dll's with photoshop therefore it wasnt beyond the realms of possibility that something had become corrupt.
BTW, all the logs are good now!
Thanks again for your contribution,
Jim[/quote]
You're very welcome, hope this helps

Wow, I am impressed that such a large, detailed thread exists on this issue. I just wanted to share my problem/resolution with mup.sys freezing on my computer.

I had this problem after upgrading my motherboard. I originally had a Matsonic motherboard with a pentium III 733 mhz CPU and 256 mb pc133 ram. I upgraded to a Biostar NF325-A7 motherboard socket 754 with an AMD Sempron 64 2800+ CPU and 512 mb pc3200 ram.

After this upgrade I got a blue screen followed by an immediate reboot when trying to boot windows XP normally. When trying to boot in safe mode, it would freeze at mup.sys, then eventually blue screen and reboot.

I tried flashing the BIOS, no luck.

I did a windows reinstall, and yay, it worked! Take that, mup.sys!

Hi, Joe. What you ran into is very well-documented, both in this thread and on many other sites on the 'Net. You can't just take a WinXP instance that was installed on one machine and expect it to boot properly on a machine with a different mobo/CPU.

You already found the answer:
http://support.microsoft.com/kb/824125/en-us
http://www.theeldergeek.com/replace_motherboard.htm

I fixed it!
Use a Windows XP SP1 CD and change the bios order so that you boot off it.
Boot the computer using the CD
Go into the recovery console (hit R to repair at the first screen)
Enter the command chkdsk /p (there is a space between the chkdsk and the /)
(As suggested by William Gaebelin III ln Oct 20th)
This found the problem on my disk and repaired it)
Then Boot off the Windows XP SP1 disk again and this time do a repair of Windows by selecting the option that installs windows. It searches for previously installed versions, select the 'repair windows" option at the second screen. (This takes ~40 mins)
When finished your data will still be intact.
You will need your licence key again (usually stuck to the side of your case)
Your will also need to update to SP2 (Service pack 2) again (either using a SP2 CD or downloading and reinstalling again), then you will need to download the ~x78 updates since SP2.

Okay, so I have a friend that had this same problem. I'm going to school for computer networks so any problem my friends have they come to me with. This one really stumped me.. I did it all from stripping down to basics, replacing parts, the whole deal... Then it happened to my computer, so as you all have encountered its a little more serious when it's your baby right? Anyways I'd like to help someone with this similar problem.

Here is what I experienced.

Freeze at boot (Win XP SP2)
Cannot boot in safe mode/freeze at same mup crap...
Cannot install fresh copy of windows (freezes as well)
I popped out my CMOS bat and still no changes.

THE RESOLUTION = NEW CMOS BATTERY JUST AS JIM RUNKEY MENTIONS IN HIS POST EARLIER..... THANKS JIM!!!!!!!!! You saved a young man from going bald

I really hope this helps someone else because I experienced how frustrating this problem is.

GOOD LUCK ALL!!

Someone also mentioned an ICPA power management function in the BIOS that must be ENABLED for xp sp2. This is true as well but instead of freezing it will be stuck in a boot loop.

I was reading about this problem because i was having it. what i did to fix it was go in to the recovery concole and changed the dir to c:\windows\system32\drivers and renamed the MUP.sys to MUP.SYS.old and rebooted the system. I seem to not be having any problems. check Device manager and all the hard ware is fine. This is my Quick fix for this problem. I think there is some windows update or app/driver that is using this file, but i am unable to find out what is mup.sys for?

OK this is killing me, i have read through so much of the stuff in here and haven't had any luck, i was hoping if someone had any ideas that would be great, but here it goes....

just as everyone else, it started as a auto reboot once in a while, then it got more continuous, until the point that it would freeze during boot up, i tried to boot in safe mode and as the post says, would freeze on mup.sys. i have taken my hdds out and put them on another computer to verify they both still work. They did, thank god, i tried to do the automatic recovery and to no avail it would freeze after it loaded the drivers and proceeded to start windows. i took my os hdd and formated it on another computer so it would be fresh and i would attempt a new install. yet again windows setup would freeze after it loaded the drivers. I have taken the computer apart and cleaned and reinstalled everything, i have tried different ide cables, i have unhooked my dvd drives, i have tried with one hdd and not the other. I have flashed the bios, cleared the cmos and replaced the cmos battery. Tomorrow I am trying a new graphics card to try and eliminate what other hardware issues this could be, cause that seems to be all that is left. I have also used different memory sticks, switching from 1 and 2 trying them in all different slots. anyone with any ideas would be greatly appreciated. thanks


Asus A7v8x-x mobo
amd athlon 2400 xp
radeon 9600 pro 128mb gfx card
2 60 gb hdd

Wes, you've talked about HDDs and cards, but you haven't mentioned anything about other interfaces (USB, 1394, etc.). Have you tried removing all unnecessary USB / 1394 / parallel / serial / other connections?

If you're using a USB mouse or keyboard, have you tried using a PS/2 mouse and/or keyboard? (If you're using a PS/2 mouse or keyboard, have you tried using USB?)

During startup, shortly after loading mup.sys, Windows goes through all the various hardware interfaces and initializes them. This "mup.sys hang" signature is often a result of a problem with one of those interfaces. Make sure you've only got the bare minimum critical connections established, and see if that changes the boot behavior of your system.

You might also try disabling unused interfaces in your BIOS, if you have options to do that (parallel ports, serial ports, USB ports, etc.). If a faulty interface is your problem, disabling it in the BIOS will prevent Windows from trying to initialize it and get stuck there.

Good luck,
Jim