Is it only Bad Company 2? It could be driver related. I've had similar things happen with my card. It only happens in Bad Company 2. I do have a different card and from ATI but I've had others with all different cards experience the same thing. the GTX 460 is relatively new. You could always wait until the next driver comes out and see if that remedies it.
However, I would also want to check the hardware. I normally use OCCT and run the GPU test with error checking on. I let it bake for a while and if there are not errors you are good.
What is OCCT?