Most likely what is happening is that you have a shortcut on your desktop that points to the true file (which the log shows as located here = Running from C:\avast! sandbox\S-1-5-21-213686681-1849411641-3850617695-1000\sfzone\C\Users\Jeff\Downloads).

If you have to, download the Fixlist.txt file and a copy of FRST64.exe to a USB drive (you can do this on a different computer if you have to). Plug the drive into your infected system and either move the files onto the desktop or just run them from the USB drive. The desktop will be faster but either one will work.