i dont know if i made it clear in the topic
this is what happens..
1. When i on the UPS power the computer starts.. well it doesnt boot but the fan starts working. ( i touched the hard disk.. but it doesnt vibrate ) so i guess the power isnt goin to the HDs or cd roms
2. When the Computer main power button is on then the computer starts to boot normally

and then wen you shut it down
the monitor goes to standby all seems allright .. but u get the fan on and the hard disk still vibrates..

it stays like that till i off the UPS

thanks in advance for any help

Sounds to me like you have one of two problems.
1. The UPS is underpowered and cannot supply enough current for the system power on surge.
2. You are suffering from a "floating ground" This is what occures when you have some components on UPS power but other components on another UPS or on wall socket power. What happens is UPSs issolate the ground reference from the actual building or grid ground, so you end up with multiple ground references that can lead to major voltage irregularities such as the 5v line being fed at a much higher or lower voltage. A way to check this is to unplug all peripheral devices, USB, External HDDs, Printers, etc, that are not powered by the UPS from your system (your monitor should be UPS powered) and see if you have any differences. Another thing. With a few exceptions LASER printers should NOT be plugged into a UPS. The exceptions are if you have a true sine wave UPS and if it has a very high VA rating (like 1600VA or better). The reasons for this are twofold. One a sawtooth type UPS output will play havoc with the motor timings and may fry out the printer. Two, laser printers use a high power halogen bulb inside the fuser to heat it, and it draws way too much power for most small UPSs to handle.

Gerritt

thanks for the reply but mate.. replace the UPS wit the main power line
same thing happens

for example if u switch the main power the same thing happesn.. UPS is just an intermediate..
sorry for not tellin that in the first post