More likely that someone you know (with your address in their address book) has an infection. Mass mail viruses will often use addresses taken from the address book on the machine they're infecting as the return address.

I have firewall and antivirus (Norton) running permanently and do regular adware checks too, so when I get bounced email like that my first thought is always that someone else has the virus.

If you have antivirus software running, this is the most likely. If you don't, it wouldn't hurt to get hold of one (there are free scanners available) and check your machine out to be sure.

Mick