WAS YOUR WALLET SYNCED WHEN YOU DID THE TRANSACTION?
Becouse it seems you where on a fork, that transaction doesn't exist.
Is not a placo wallet error if you send coins when not synced....
ALSO. SENDING HUGE AMOUNT OF COINS WHILE WALLET IS NOT SYNCED.... THAT is NOT ACCEPTABLE... (as you said)...
Anyway... you can send me your wallet.dat if you want and I will take a look.
No promises btw.