Hi!My PC crashes and restarts every time i'm trying to launch Arma 2 or Stalker Call of Pripyat.It works fine with another gamesIt started when i upgraded my gpu (gtx 680).I never had any problems with my previous card (gtx 470).
I would uninstall all your nvidia drivers first, run CCleaner/driver sweep etc and then do a clean installation of the latest ones. You could try the 301.24 beta drivers to see if their any better?