The same thing has been happening to me. I don't think it is a virus, I think it is a worm. It seems to have started with an email I opened (but not the attachment). The weird thing was that I received the email from an email address of someone I know. Since I opened the email it now seems to be shooting off these weird emails to people I know from my email address. It seems to be attaching to every email address I have in my address book.

I think it is some kind of email worm, but I also ran a couple of different worm fixes and it just tells me "no worm detected". Can't figure out how I got affected and how it could start from an email from a know source. I never open emails from someone I don't know. I started on my yahoo email account, but now it is affecting all my email accounts.

So if anyone hears of a fix, please let us know. It is getting rather embarrasing to get business associates asking me about strange emails.