I've had repeated crashes due to probably driver issues that I can't fully diagnose. Mostly it's just been annoying - but the latest one has apparently wiped out all my progress. There's no option to continue play, I can't load levels, and my achievements are wiped from both the game and Galaxy.

(I don't care about achievements, but it suggests a fairly fundamental loss of data)

Any idea of a way I can restore things? I'd nearly finished the game and am not enthusiastic about replaying it in the hopes that the same thing won't happen again.