I'm running McAfee Managed Virus Scan (whatever they call it this month), and it has never seen anything.

I narrowed the problem down to KB959426, which is some bizarre "blended threat' fix, where someone convinces you to download a file to the desktop and then search in some way that loads the file, but it seems to be an IE thing, which again I don't use for anything off the LAN. I've disabled that update for now, but am hoping to find a better answer.

Thanks for the hints. I'll let you know what I find.