I've been having this problem for about a week now. If I play Heroes of Newerth or Call of Duty BlackOps either way my system will freeze up and make the games unplayable. Battlefield Bad Company 2 also freezes up but not AS bad. What happens is basically when I start playing the game freezes an insane amount making it completely unplayable. Call of Duty Black Ops varies slightly in that it freezes on the main menu screen Counter Strike Source runs but doesn't run well at all. I get about 60fps with all settings turned to the lowest possible.
I have not made any hardware changes since the problem. My system is as follows...
Core 2 Duo E6600
4GB DDR2 RAM
Nvidia GTX 460
I've tried some stress tests and monitoring temperatures when in game. My CPU tends to stay around the 50-60 mark when being HEAVILY stressed by tests but 45-55 in games. It's load remains at 100%. GPU stays around 45. I've tried reinstalling windows (switching from 7 to XP64bit) but I've had no luck what so ever. My PC used to play these games fine (well, I never got to test BlackOps as it's newly released) but it doesn't now :S I can't really find what the problem ACTUALLY is...
Your cpu might be holding your gtx 460 back a little, that said you shouldn't be freezing in games. Mybe stuttering or poor frame rates but not freezing. I recommend running memtest as a boot disk to verify your ram is running properly. And if all possible, give your e6600 a little overclock, to around 2.8 to 3.0ghz.