I play a game or two online with smooth gameplay, then all of a sudden the screen freezes, and the game crashes. I thought maybe it's because I put in a command to turn AA off (r_postmsaa 0), but no it isn't that. Really frustrating.

Specs:
-Alienware M17xR3 (lap top)
-Intel i7 2670QM
-AMD Radeon 6870M
-8GB RAM
-Windows 7 64-bit

Notes: Playing on extreme settings. I have DX11 on and High-Res Textures on.