Hi
If you have run the virus scanner and have a current definition file/subscription, and scanned with the newest version (181) of AD-AWARE, you're probably not the source of these emails. In fact, it's unlikely.
I have the same problem on a daily basis with the email accounts associated with my cablemodem company, although I've never given them out to a soul. In my case (and maybe yours) it is just some spammer who either found your email address posted somewhere on a web page, or is randomly trying every word to "spoof" in the FROM field of messages.
You can verify the true source by going into the original message and checking the headers. The headers will tell you the original IP address (machine/internet location), machine name, etc from where it originated. Just don't open any attachments. If you want to be sure, forward it to me and i'll do the detective work for ya.
When someone receives this from "you" (chances are its someone you won't know, because it doesn't infect your contact list and originates overseas), some times they'll write back with a nasty email - assuming you to be the source. Since the spammers get the recipients from some place other than YOUR contact list, it's unlikely to make it to anyone you know.
Such a waste of talent. I wonder if anyone actually buys/trusts that kind of thing over the internet. They're probably tic-tacs in a fancy package
Mike