I too am having this problem. I only ever installed the "Install" disc, as recommended. Problem happens at the same point every time. Game (not xbox) restarts with that "alert, your game was restarted..." blah blah. Also, I've got a 250GB hard drive the new slim edition, but here's what I've tried so far:
- Tried clearing the cache.
- Tried running the saves off a USB.
- Tried installing the "Install" disk to the USB and run everything off there. Although here it would freeze a lot too, so I'm thinking the USB speed wasn't enough to keep up.
- Tried deleting a big chunk (up to 50GB) of old games and data on the internal hard drive. Did a fresh install. Didn't help.
- Formatted the internal hard drive completely. Did a fresh install. Didn't help.
I'm currently out of options but I'm going to see if I can get a different install disk and go from there. I will post my findings when I try it but it will have to wait until the morning.