а что debug.log говорит?(он в той же папке что и wallet.dat)
2014-09-16 05:08:52 Added time data, samples 10, offset -1 (+0 minutes)
2014-09-16 05:11:46 CheckForkWarningConditions: Warning: Large valid fork found
forking the chain at height 320713 (0000000000000000043f00f9d8e00d5e2b2c52704904f8eb0db33016770a0a97)
lasting to height 320923 (00000000000000002253d4592ffb2487ab3b5955590c69512cde929391672242).
Chain state database corruption likely.