Run the remove_old_files script (take out your wallet.dat first)

This isn't a problem with the wallet, we think a whale/whale(s) came online on an older fork and disrupted the blockchain. If everyone updates again, we should be good.

According to the dev:

"Someone rich came online and made a lot of stake, the peers he was connected to, updated, but the rest were late and had other blocks of same height
and it was a long fork that confirmed blocks from both forks, and once it confirms, it can't auto correct it"