Am not sure what might have gone wrong with the tx as being a single UTXO and being very old it should not even require a fee.
Try starting the client with the -rescan commanline option perhaps?
You could try that but assuming you are wanting to *not* broadcast that tx now then you should stop running bitcoin (as it will keep trying to broadcast the tx every 30 minutes or so).
And assuming you have a backup of the wallet that was *prior* to that attempted tx (but does have the original 9.8 BTC) then replace the current wallet with your backup (keep a copy of the current wallet *just in case*).
Assuming all looks fine when you restart Bitcoin then you should upgrade your client to the latest (you need to do this by May 15th anyway).
