Restarting computer, not fault of XP?

My computer has begun to restart itself every time I turn it on. Sometimes it waits until I get into windows and sometimes its while its booting up. Does any one have any suggestions on what could be causing this problem? Thanks!

Hi

Faulty OS,
Faulty PSU
Faulty Board.

Check the board capacitors for any that look bubbled on the top and rusty marks on them, sure sign they are failing.

Swap out the PSU.

Press F8 after the PC Post screen and before the XP logo and from the menu choose safemode and see if it restarts in that. If it doesn't its definately an OS fault, if it does refer to above.

Remove all devices apart from one stick of memory and the VGA card and the bootable drive, now see if it does it, if it doesnt then one of the items removed may be responsible, if it does refer to above

Just some suggestions...

Regards