Must have been something running rampant today. Per John's advice, I did a search on ComboFix, was sent to BleepingComputer.com (my sentiments exactly). In their virus forum, found half a dozen posts from today from people describing the same problem I had. No DOS box, no regedit, cannot edit batch files ...
I downloaded ComboFix, ran it, and IT'S FIXED! Got a DOS box, got Regedit ... It printed out a big old log .txt file, but I can't make anything out that tells me what it did. THANK YOU JOHN! Now if I can only figure out how I got it so I don't do it again ... Karen

