There is a really bad graphics glitch in Crysis 2 where all the light sources are constantly flickering. It is so bad it renders the game almost unplayable. The only way to solve this problem is to either run the game in windowed mode or turn off crossfire/SLI. Apparently it only does this with multi-gpu setups.

I hope EA/Crytek releases another patch for the game fixing this problem. Or perhaps ATI/Nvidia can fix this with new drivers.