Computer restarts when exiting games?

[chgode]

Whenever I play Return to castle wolfenstein or call of duty for a extended time and then exit out my computer will restart...but if i just start the game up and then exit out without playing or playin very shortly this doesnt happen.

Computer never restarts when i play counter strike either...These are the only games i really play.

I tested both my (wd) hard drives and they are both good and functioning properly.

any suggestions?

xp
p4 1.4 gig
320 sdram
geforce t1 200