I have a home build pc with at Intel quad core (Q6600) oc from 2.4 -3.0 ghz, a asus gtx550 ti just slightly oc, core volt 1100, core clock 979 and memory clock 2104, 8 gb kingston hyper x ram and windows 7 64 bit

I have this problem where crysis 2 stops working,crashes or no picture, but i can see and hear that the game is still running, it does that often when a mission almost is finished, it is just running fine and i advance in my mission and boom then it often happens, it crashes or the problem with no picture but the game is still running(only thing i can do is to start all over again,terminate the game and then start from where my game is saved, sometimes i log out )

The oc spec of my gpu is not more then a asus super oc card and my cpu can be extreme oc to 4.0 ghz but my motherboard limited is 3.0 ghz, have no problems with heat

Any surgestions on a solution to my problem, is it a oc,heat problem?