I have had this problem since closed beta! It has happened during the away missions of Starbase 24 (crashed 3 times!) and during Stop the Signal (crashed once). The game stutters for a little bit and then it says the gameclient has crashed. It seems to only happen when there is a lot going on and ONLY during away missions - e.g. 3 of us throw grenades, lots of other people being knocked back/firing weapons etc.
If I move the mouse and look in the opposite direction, the game is fine. Seems like there is an error in the game engine. Have bugged this many times, even since closed beta. I know I am NOT the only one with this problem.