I was recently paid to my BiddingPond auction's address by the winner of an auction there. He messaged me "payment sent," but my Bitcoin client (0.3.20.2) has the latest blocks and the transaction isn't showing up.

I know the transaction happened, though, because it shows up in blockexplorer.com with the same amount as the winning bid!

Two possibilities:
   1) BiddingPond.com shenanigans (hacked account, hacked site, or dishonest operators substituting their own address)
   2) buggy client that lost a receiving address

What gives?

Wait, I think it's because this is a very old BiddingPond.com address and I changed wallet.dat files since then. I'll have to look through my backups.

I hope this is it...

I emailed BiddingPond and all is well -- this is their address, and they didn't have my address on file, so they couldn't forward the funds.