Hi, I had the same problem with freezing game. But i solved it this day! It was caused by graphic card fan speed! I have Nvidia G-Force GTS250 and i had set dynamic fan speed. When i started playing Arma, graphic card automatickly boost fan rotation and game froze. So I set only 35% of fan rotation (speed) and now i can play the game without any freezing! Try it, it may also help you. It helped me.:bounce3:
Excuse my English.