Yes, I have received a VIRUS from myself, and that's where to start looking. Click on "view full message header" and you should be able to see who it really came from.

One of the most common worms Klez will pick names from the infected computer, and places them as the return address. So the person getting the mail, writes back to you, and you didn't send anything.

So if you haven't deleted the message, look and see who it's really from.

I have been getting a couple a week from a specific person and wrote back to the Original sender, not the spoofed return address. Maybe she will run a virus check now?

So it works like this...
Infected computer

Virus looks in files for people to send to

Virus looks for other mail addresses
Infected computer adds YOUR name to infected mail and sends to people from the computers storage.
The real sender is in the origin part of the full header, but Your email address is listed as the sender and return address.

Ever get a bounced mail, user does not exist, from yourself, but you never sent a message and don't know who that person is? Same as above.