I recently got an Xbox 360. It came with GRAW. I got up to the second last level and when I enter the screen to selcect my weapon and teamates it frezes. This was on easy mode and it is the same on hard mode. I though it was the disk (maybe it was scratched?). But today my friend lended me his own game GRAW. It did the same thing. Whats wrong?Is there a problem with my system?