Hey AngryMob.
Try clearing your consoles cache and re downloading the latest title update.
Go to memory> highlight the HDD> press Y> select yes when asked if you want to perform maintenance.
Then put the game disc in while connected to LIVE and you will be asked to re install the latest title update.
Alternatively if you have one try installing the game to your HDD.
If this still does not help check your NAT and make sure it is set to OPEN, if you need instructions on that let us know.