🚀 go-pugleaf

This sounds like the same problem I had with the 7.0.9 upgrade. After installing it, my computer would not even recognize that Reader was on it, and kept asking to install version 5.0 when I attempted to open a PDF file.
I tried all of the uninstall/reinstall tricks, but the bottom line is since attempting to run version 7.0.9, even installing version 8 doesn't work.
I ended up having to locate an installer for version 6.0.1 to get something running that would work with my net browsers.
As for the registry, I had quite a problem there. I discovered that for some reason the editing permission for the OPEN command in "HKEY_CLASSES_ROOT\AcroExch.Document" had changed, and could only be deleted by using Regedit32. I had to right-click on the key, and change the permission to allow editing before I could delete it.
As for Reader, NOTHING higher than 6.0.1 will now work on my computer.