Actually, in this case Shatnerfan may not be infected. Klez (the virus mentioned) has the rather odious ability to take the address book on the infected computer and send copies of itself to some of the addresses, purporting to be from the other addresses. If Shatnerfan had said he was getting virus related bounces in his earlier question I could have been more specific. However an extra nasty feature of this virus is that it sends out its own returned mail messages to addresses, with the virus attached, so chances are, if the message has been opened or viewed in the Outlook preview pane, then Shatnerfan is infected. It also finds documents, pictures and so on and sends these out too. Plenty of people have found their friends now have some pretty interesting private stuff. First thing is to find out whether you're infected. One sign is that your antivirus may not work - Klez screws this up too. Then I'd suggest using the symantec cleaner which can be found here
http://securityresponse.symantec.com/avcenter/venc
/data/w32.klez.removal.tool.html
It also gives a better explanation than I am giving here! Follow the instructions then reload your antivirus and download the latest definitions. To be extra safe I'd then run a free utility (30 days) called the cleaner which you can find here
http://www.moosoft.com
This will check you're clean and also detect/clean any other nasties that have got on your system. If you're careful then by examining the returned email notifications you could find out who of your friends is/was infected. If you're not sure, leave them as it is safer not to touch them.