I've been having a problem since I built my PC. Sometimes when I start a game up it'll run very jittery/choppy. It won't stop until I restart my computer. It really only applies to Counter-Strike: Source and Crysis so far, I'm not sure why it only happens for FPS games. I've play other games like Oblivion and WoW and it hasn't ever happened with those. I'm not quite sure the problem lies in the video card, but I'm thinking it does. I have an EVGA GeForce 8800 GTS 640MB graphics card with up to date drivers. Does anyone else have this problem, and can anyone help me solve it?