Did you have an ATI card in the system previously and didn't uninstall the drivers properly(driver sweeper in safe mode)?
Are you using the latest drivers from the Nvidia website?
Do both Windows and DirectX have their most recent updates?
Are you sure your OC on the processor is stable? Is the card OCed and if so are you certain it is stable?
Did you try reinstalling the game?
previously I had the Nvidia 6200LE
yes am using the lastest driverfrom Nvidia
DirectX-yes and windows-not
yes I think that the processor is stable but the card no
yes I tried many times to reinstall the game