When starting a mission, just before my aircraft touches down, the game freezes. I can sometimes get it to work after shutting the game down and restarting. When I restart the game, sometimes it works until I start the next mission and it freezes again. It started this after about the 4-5th mission.
I am running Win 7.0 SP1 (64 bit), with a 2.0 GHZ Intel i7 CPU, 8 GB RAM, NVIDIA GTX560 video card.