XBOX 360 Modern Warfare 2 thread(*MERGED*)

Hey guys, figured I'd come here for help. My little cousin called me because he's having issues with his copy of this game. He says that he can't get online to play, but if someone invites him to a game he can play online just fine. He's already exchanged the disc out at his local GameStop, he's also contacted AT&T and XBL. None of these things fixed his problem. Has anyone else had any issues like this?