WinXP freezes playin GL games

when im playing OpenGL games like RTCW my systems freezes after a while.Sometimes after 1 minute, sometimes after 5 minutes. only chance is to press the reset button.
I´ve a GF2 GTS and tried all drivers (asus, detonator and it were the newest one) and have also the latest via chip driver installed
Always the same, is there a chance to fix the problem? Just want to finish RTCW without rebooting every 5 minutes.