Desktop

Check out these solutions to the same problem from the guys at Experts Exchange:

http://www.experts-exchange.com/Operating_Systems/WinXP/Q_20706552.html

There are a few software possibilities mentioned in those threads.

If it's not a software (XP) issue, it may be a heating and/or power issue and/or hardware issue. Verify that the power supply is sufficient for the hardware installed. Try to replace the hardware components one at a time. Replace the RAM one stick at a time Try some beefy cooling fans.

...and i like to boot from a floppy or cdrom and let it sit and cook while i am thinking about next steps. if it shuts down in 30 seconds with a boot disk, i would say try another power supply...

Is that PC connected to a network? If yes, disconnect the network cable, the boot it again. Does it shutdown again when you login? Are there any messages prior to the system shutting down?

sgt_shultz nailed it. First open it up and see if all the fans are
spinning. Processor fan, power supply etc. If they are not thats
the issue. If they are then boot from a CD or floppy to remove
the installed OS from the equation. If it still fails it's hardware.
The easiest thing is to try a new power supply, but depending on
how new it is that will void any warranty.

Good Luck,

razz

I don't think it's power supply because the problem of power supply is it reboots over and over again or from the start it has no power. I think it is a virus that causes the shutdown. Update your virus scanner. If you can't, you have no reinstall your windows from a cd or a bootable disk.

Press F8 as it boots and turn off restart on error.

You will at least get to a error message or blue screen.

Lee

check to capacitors exit to the CPU
if they are flat on top they are good
if not they are bad.
if they bad you will have to replace the motherboard

You should ask your tech mate if he has just run Adaware.

Try this site.

http://www.opentechsupport.net/forums/showthread.php?threadid=20552