I didn't see anyone answer. I'm pretty sure I have understood this properly:

• The double arrow is shown when a transaction is made that has inputs other than are in the wallet of the QT you are running. It was created by another client that has your privkey and other privkeys that you don't have.
• The n/a address is shown when there are more than one output that is not a change address in your own wallet. In the transaction you are mentioning, none of the outputs are likely a change address, so QT can't know which one to show.

This means that if your wallet file was stolen, the thief imported other addresses before they sent, or they are creating transactions with different software that they importet you privkey and other privkeys to.

-OR-

This kind of transaction is actually most likely to be caused by the real owner after he/she has been exporting and importing addresses and been playing around with wallet files. In this case the coins weren't stolen but just transferred by mistake to another address you own. Coins might not be lost after all!