I copied my wallet.dat to a different location and deleted the entire Aidbit folder in ..\AppData\Roaming

I then launched the wallet and it's redownloaded the blockchain again.  I just hit a strange hiccup when there were about 125 block to go, where it got stuck for a few minutes.

wallet.dat is copied back again now and everything is looking fine, although it seems that mining on the P2Pool for over 24 hours yielded no coins at all.  Going to give the official Felix pool a try now.