It seems some of your inputs have already been spent... I attempted to broadcast this transaction and got: "Missing inputs (code -25)" Because those inputs are now "missing" (ie. confirmed in other transactions), this transaction is no longer valid. I would suggest the following:

- Make sure Bitcoin Core is fully synced.
- Shutdown Bitcoin Core.
- Make a backup of the wallet.dat
- Start Bitcoin Core using -zapwallettxes command

It should remove ALL transactions from your wallet, then rescan the blockchain for "confirmed" transactions that relate to your wallet addresses. Once it has finished, you should see all your "confirmed" coins... and this "impossible" transaction should no longer appear.

You can then shut down Bitcoin Core and restart normally (ie. WITHOUT the -zapwallettxes command).