computer restarts on it's own

[papichulo1968]

The problem only seems to be happening if I play my pc games, short into the game the pc reboots, sometimes is the screen that just go blank. I have a compaq presario 2.2 gig athlon xp processor, win xp, 768 megs of ram, ati radeon 9550 256 megs onboard. I thought maybe was heat realted issue , but other than with the game the pc nevers reboots on it's own. help please. the game i been playing is world of warcraft

 

[T3C]

Heat? The computer is working a lot harder running the game then it is web browsing.