The computer wont run for more than a couple minutes without restarting.. and most of that time is spent waiting for it to boot up. It usually restarts itself at the XP Login screen while I'm attempting to type in his (quite short) password. The one time in ten I get lucky enough that it lives long enough to actually log into Windows, it restarts itself sometime in the next minute or five.
It's really frustrating!
A couple of the times I got it to log into Windows, it gave the "Remote Procedure Call Terminated Unexpectedly" type countdown message that Google searches attribute to the Blaster worm, but I wonder if it has that. Will that cause it to restart before you've even logged into Windows? (<---- GeekU student, asking about malware. Maybe you shouldn't answer that part )
I tried changing the service so that it would take no action instead of restarting, but that didn't seem to change anything (actually, it restarted pretty quickly after I applied the setting, so I'm not sure it took).
The computer is very old, but was reformatted recently, and while he's not very tech-savvy, he's responsible about keeping everything updated and not messing with the kind of things that get you infected. I'd be a little surprised to find he had a virus, although of course it happens to everyone.
It's nice and clean inside, so it's not overheating or anything.
Anyways, he lives a couple hours away, so I wont be back in front of his computer until next weekend, but I thought I'd try to gather some ideas before then.