Halo 4: "Players failed to load content"

Hey guys, I have been unable to play Halo 4 for a while now because when I try to load anything, I get this message: “Players failed to load content, a player may be missing downloadable content”.

This happens in campaign, theater, forge, custom games, matchmaking and spartan ops. The only thing in the whole game that I can load is the prologue in the campaign.

This happened to me around the time I first played forge test playlist, I had a good few games, and then it just stopped allowing me to load anything.
I have tried cleaning the disc, deleting system cache, deleting all Halo 4 content and re-installing disc 1. I have tried playing on another hard drive, I have tried another Xbox 360, I have tried playing on offline accounts and another online account. None of these things made a difference.

As far as I know, the only thing left to try is using another Halo 4 disc, but before I buy another one I just want to know if there is anything else I can try?
I love Halo 4’s campaign, and as much as I am disappointed with Halo 4’s multiplayer, I still enjoy it and still want to play it!
This is very frustrating for me so any suggestions anyone has would be much appreciated.