The game will freeze at random times, quite often (every 20 min or so), and drop out to windows desktop, but still running the game. I have no control of either game or windows until I alt+tab to windows. Once to windows, I cannot reopen the game and am left to close the game. This has only been happening since the last update. I have tried updating my graphic drivers (nvidia gtx 260 x2 in sli), and all windows updates, with no change; the problem still occurs.