mass-mailing worm

Ok I have some questions about a mass-mailing worm and I do understand how the infected emails get sent out to appear as though they are from me.
I belong to a Yahoo Group that has 400+ members and it seems like at one point or another that several of us that are friends have received an infected email with an attachment from one of the other ladies but neither of us had sent that email. We all have done virus, spyware, malware scans etc.. but have found nothing. Before I ask my specific questions I need to let you know what has just happened recently as well. We all post on the Yahoo Group message board for the group that we belong to and yesterday a post was made to appear like it was from this one lady but she didn't post it. I have looked up the source details and there is no originating IP but it used her Yahoo Profile username when the post was made and the way that the post reads we know its a virus.
Please see the attached file for details.

+++ Attachment: No Virus found
+++ Panda AntiVirus - www.pandasoftware.com



[Non-text portions of this message have been removed]
That is the full portion of the message board post I didn't include any personal information.
Okay now my questions..
1. How do we find out who is infected when there is such a large number of people who could have us in their address book?
2. How do we locate the origination of the message board post?
3. Can I be infected even though scans do not show anything ? I run my AV, and spyware stuff often and deligently and keep everything up to date. I am very complusive about that I have to run things more frequently then is recommended and keep everything up to date on almost a daily basis. So you wouldn't think I would be infected if I do this compulsively yanno.

I am sure that there are several people within the Yahoo Group who >gasp< in this day and age don't use any antivirus software >gasp<.
Thanks for any help/advice anyone can give me .
shewolf

 

try mcaffee advert stinger. send friends to mj geeks for download of said stinger . some virus disable AV scans this is a independent scanner. (runs without installing in your system. )