Mine's been doing this ever since the dashboard update. It was fine for approx 15 hours of play before the update, not a single crash or glitch. After the update it's crashed constantly on all 3 game modes (story, co-op, challenges). I'm basically never going to get the last few achievements because it frequently crashes before the end of level/challenge save. My other games are fine so it's probably not my console at fault.
Shame. It's a nice little game, a good change of pace from all the RPGs and stuff I've been playing.