If your wallet is password protected and damaged I am not sure how you will solve this problem!
It says in the OP the wallet isn't encrypted according to his client, and last transaction is from August 2011, Bitcoin-Qt 0.4.0 with encryption wasn't released until a month later.
Or the client got it wrong and encrypted it on his own, or it was some sort of watch-only wallet.
.4 clients (encrypted or not) often left private keys able to be extracted in plaintext, it was a known bug. In my case 50% of the private keys were left in the encrypted wallet in plaintext and there are other places to look for traces as well. We wrote our own stuff but there is code floating around.