Ok, now I know I'm on the right forum for this one.
Two nights in a row, my game has consistently frozen under the exact same conditions. The other night, I was playing Beast mode with a couple of friends of mine on Checkout. We made it all the way to wave 12 and my game froze up on me. I immediately ejected the disk to prevent my player data from getting reset, no big deal. I chalked the whole thing up as a fluke. Then last night, I was playing Beast mode with a couple of my friends again. Same scenario, we got all the way to wave 12 and my game froze on me. I immediately ejected my disk to prevent my player data from getting reset. Conveniently, at the same time my game froze, my buddy's game froze as well. He ejected his disk, but his data got reset. He was level 32 red and suddenly he got reset to level 95 white. Fortunately for him, he made a backup file of his player data on the cloud and on a thumbdrive so everything's shipshape for him right now.
The problem is in this consistent freezing of my game 2 nights in a row under the same conditions: Private Beast mode on casual difficulty during wave 12 on Checkout. How does this happen? Is there a way to prevent this? Does there need to be a patch to fix it?