Bitcoin-Qt quit unexpectedly

I can't run Bitcoin-Qt 0.80 on Mac OS X 10.8 any more.

It starts up then says "System Error: Database Corrupted". I then click OK, and the program "quits unexpectedly"

How do I start again without losing my wallet. Is it just the wallet.dat file that I need to keep, or others as well if I reinstall? I have encrypted the wallet if that makes any difference to the files I need to keep.