Last night I was downloading Revo Uninstaller when it happened. Avast went off when it was installing. There were over 20 things that Malwarebytes found - Conduit, Great Arcade, Open Candy were three I remember. I also ran Adwcleaner. I'd ran Malwarebytes earlier in the day yesterday and it was clean then. It's not the first time this has happened downloading something from Download.com but I thought it was a fluke. Apparently not upon Googling it afterwards last night. I'm not completely sure that Avast showed 'some files could not be scanned' prior to this. I might have just not noticed until I had problems.