Resolved Question: Spam is emailing all my addresses in my address book, how do I stop this?

Something has gotten into my address book and keeps sending my contacts spam messages with my address as the sender. My friends keep asking why am I sending them spam. I am not doing this how can I stop this from happening. It seems like some kind of spyware but I have Zone Alarm which should have caught this. No virus has been sent to destroy anything just spam to buy something.