Question : Windows XP restarts at Desktop

I have a Windows XP computer that everytime it gets to the desktop it restarts.  I do not know the history of the problem other than it is now restarting at the desktop.  Does anyone have any ideas what it could be?

Answer : Windows XP restarts at Desktop

Spyware, virus, bad capacitor, bad sector in hard drive, just name a few. Do you see any error code or message appear before restart?