Computer restart issues

I have been having very serious computer issues this past week, my computer seemed to have some kind of glitch that caused it to restart again and again when I would try to boot it up in the mornings. I think I tracked the problem down to a program that Windows XP did not digest properly, but I'm not sure. I ended up rebooting the computer to the factory settings. Lost a bunch of things, but I don't think I have lost the computer. It'll be a couple of days before I know if that cured the SNAFU, or just gave me a brief respite from the issue for a few days.

I had tried all kinds of fixes before resorting to resetting the whole system, including setting back to older dates on the computer and defrag, virus check, Spybot, etc, etc, etc... none of them seemed to work, so deciding that I would prefer to send the weekend reconstructing the computer than spend next week trying to figure out how to buy a new one, I backed up whatever I could and reset the sucker. I'm slowly getting it put back together now and hope to have it sorta back up to speed by Monday morning.