I am sure many of you have seen something about the Yahoo!mail and Yahoo!groups hack recently. If you recieve an e-mail with no subject or the word "unkown" in the subject line, even if it is from a trusted friend's email, DO NOT OPEN IT.
This hack has extended to Hotmail accounts as well; My parent's email was hacked into and a large amount of e-mails with no subject were sent out to people in their contact list.
From messages I have recieved from friends knowledgable in computers, these emails if opened will deposit two rootkits on your computer, which cannot be detected by most virus scanners. I don't know the specifics; that's just what I heard.
Hopefully this helps some of you avoid this problem. Pass this message along; I know anybody that is a member of a Yahoo! group will probably have their e-mail, regardless of provider, hacked sometime in the near future.