I had the same issue in the beta making it unplayable for me.

I could play the mp fine in the retail version, but then I beat the game and now I have the same issue.

I read someone fixed this by using the latest beta ati drivers, which did not work for me.

Thanks in advance.

Bump, I'd like a dev response if possible

Didn't want to re-write, I posted on another topic about the same problem. I was able to resolve it for now, check it out. http://www.gamesas.com/forums/viewtopic.php?f=65&t=60229