A friend of mine was complaining that her desktop would randomly shut down, she thought it was a virus, I said I'd take a look at it for her. Did the usual scans, there were some viruses, and a lot of adware. Cleaned it all up with spybot, ad aware, malwarebytes, nod32 and ran ccleaner and jkdefrag just for good measure. As I was doing the scans, it would as she said randomly reboot. Even after it was cleaned up, still random reboots. Not always under heavy load either. So I ran chkdsk, same thing. It's obviously been awhile since her last format, so I backed up everything she needed, formated, fully updated to xp sp3, still randomly reboots, although it seems to be less often, could just be me. Next step I unhooked EVERYTHING from the MB, reseated the CPU, swapped the RAM for an extra stick I had laying around, still random reboots. The last time it rebooted windows came up with an error saying that I should test the RAM, and ran it through a memory diagnostic for about 2 1/2 hours without problem. I figure its down to the MB itself, although in theory it should have restarted during the diagnostic I would think. I would think PS next but same thing it should have shown up during diag. Any ideas?