Do I have a virus

I've got AVG (free)on my computer and it tells me that I (currently) don't have any viruses. But my Email (Outlook Express) makes me wonder what is going on.

1. Starting abruptly on 12-18-04, My Emails started showing "attachments" when there were none. The paperclip symbol would show on spam as well as private Emails but not on mailing list digests. Mailing lists that I receive singularly DID have the attachment symbol.

2. At about the same time, I started receiving an Email message...something about returned mail (that I had never written). I paid no attention to it. Then I got an Email from someone I didn't know who wanted to know if I had any idea why he kept getting a "mail returned" message with my Email address on it.

3. Next I heard from a friend you wrote " I keep getting messages from proadvantage or something like that to my comcast e-mail account that mail I sent to you has been declined because it has an unsafe attachment. I have NOT been sending any e-mails to you from that e-mail address because that is my business account and I only write to customers from there. Just wanted to let you know that if you are receiving mail from me from comcast, I don't know how or who is sending it, but it's not me."

I have no idea whether I have a problem or not. Any ideas what is going on???? I'm a novice at computers so please keep it simple). Thanks!

Sandy