My computer got hit this summer by two variations of klez. I had 2
anti-virus programs running and I never opened the attachments. Norton
never found either of them, and my AVG found them for 3 days before the
"unhooked" both programs. Nothing seemed to fix them.
In my research on the Klez I've found that it is a function of the virus
that it disables most or many anti-virus programs sot that it can't be
found.