The biggest thing that would affect me is HOW. I don't have an autheticator since I am scared what happens if I ever play away from it. I think I would love a way to block signing on away from the computers you allow. My bank does this. "You are trying to sign on a computer you have never used before, please answer a secret question to continue." Just ask a question that is simple if I use a computer I haven't used before. Shouldn't take long, never gets lost and my guess would protect you.

Back to the question. HOW? Did you not notice a bad website? Do you open mail on your computer? Do you download installers for programs, or just zip files? Do you update your OS when patches come out? You mention the anti-virus, but was it running in the background? Do you have it full scan your computer daily? Do you share your computer with friends/family that might do something questionable? I am not saying it isn't possible, but how the hell do some people get ganked and not others, why doesn't this happen to 90% of the people other than authenticators?

I feel sad that it happened to you. It isn't fair. I wish there was an easier way to protect things so it wouldn't happen. I would probably cry a few days for loss of guild bank and all chars stuff.