I don't get it anymore, but I used to get a security notice telling me a file had been created called C:\Program and that it needs to be renamed to C:\Program1 so that it doesn't effect other programs. I would get several of these, I got up to C:\Program8 eventually.
I too ran several virus/trojan scanners, all coming up clean. I don't know what I did for it to stop happening, but I've been clean from that notice for about a month.
Regards,
