if your funds were stolen from multibit it has nothing to do with multibit.
It means your computer is compromised. Using qt OR blockchain.info
on the same computer will make you lose more money.
But my computer was not even on.
What if the hacker had access to the wallet backup and the password? It wouldn't need my computer that way, right?
Nothing has to be running for someone to initiate a transfer of your funds if they have your sensitive information.