I'm having the same issue. I made it through 2 missions in the campaign, and when "Forerunner" went to load, the screen froze and I got the disc clean error. I figured it was a manufacture defect since the disc is perfect, so I exchanged it for another copy. Loaded up the game where I left off, same issue. Rage.
Called up Microsoft, they said many people are experiencing the problem and that 343 was "Working on it.". They gave me a reference #, and said I would receive an email soon in regards to a fix soon. So it's not your system. 343 put out a game that wasn't ready for the masses. Before the game came out, my faith that Halo would be restored to the awesomeness that Halo 3 was has now completely died. 3 games in a row of garbage. What I did play of the campaign was boring. It's a carbon copy of Reach attempting to be Halo 3. I basically have a glorified $65 Free AOL disc with a Halo picture on it.
If they don't up with a fix by this weekend, I'm pursuing a full refund. Which is hubris anyways, because we all know that once you purchase a game and open it, they have your money, and you're not getting it back. But I'm not easily pushed over.
