airmess, I had the exact same problem in AH1 with any 190 and 109 cockpits, it was due overheat of the card (GF3 Ti500). At least in my case it was not inmediate, after some minutes I got few of these squares, then more squares and then even moving squares. I solved the problem adding a more powerful fan to the card, but this problem was only present with AH, never with any other game.