Sorry Protools1983. Im not a some fat ass kid sitting in their moms basement who spends all day reading and replying to message boards. Unlike you i have a life and dont sit in front of a computer all day talking crap just to boost my ego and self esteem. Just saying
After I got corrupted the first time and started over, I just pulled the ethernet cable out of my console before playing single player and it hasn't happened again. I hate to think what will happen when I plug it back in and play contracts, but at least I've backed up my completed save.
Sad thing is, if this problem is what I think it is, just backing up your save is not going to help a whole lot.