This. More than likely the btc stealing software. Face2Face is not always a good decision. Never allow someone to install something, or put something into your computer. I would have had him write down his address, not bring a flash drive. Your bitcoins can possibly be returned if you backed up your wallet with an encryption. He shouldn't be able to do anything with them as long as you did that. Also why do you post this in the noob section? Shouldn't this go in the support section?