This error is not related to your problem. It's just that the wallet contain a new type of data that the bitcointools is not aware of. (namely, the most recent block that this wallet was synchronized with)

Do you have a thread where you describe the scenario that led to hung transactions ?
edit: I assume this is the one. My advice would be to wait a bit for the import/export private keys feature to be formally released in an official version. Then you can dump your keys to a text file and import back the relevant ones to a fresh wallet.