Dick -
I think you are up against something different. As Paul suggested you probably are in someone's address book and the virus is using your email info as a "Send From" name. So it appears to be coming from you but in actuality never was even close to your computer. This is from Symantec's site:

In addition, the worm searches the Windows address book, the ICQ database, and local files (such as .html and text files) for email addresses. The worm sends an email message to these addresses with itself as an attachment. The worm contains its own SMTP engine and attempts to guess at available SMTP servers.

The subject line, message bodies, and attachment file names are random. The from address is randomly chosen from email addresses that the worm finds on the infected computer.

So the problem is your are in someones address book who has the virus. It randomly chose you for some email to propogate itself to other unsuspecting people.