Let’s do a full clean re-install;

Download Firefox For All languages And Systems {web link}

Save the file. Then Close Firefox.

Using your file browser, open the Programs Folder on your computer.

Windows: C:\Program Files C:\Program Files (x86)

Mac: Open the "Applications" folder. https://support.mozilla.org/en-US/kb/how-download-and-install-firefox-mac

Linux: Check your user manual. If you installed Firefox with the distro-based package manager, you should use the same way to uninstall it. See Install Firefox on Linux; https://support.mozilla.org/en-US/kb/install-firefox-linux

If you downloaded and installed the binary package from the Firefox download page, simply remove the folder Firefox in your home directory. http://www.mozilla.org/firefox#desktop ++++++++++++++++++++++++++++ Look for, and remove any Mozilla or Firefox program folders. Do not remove the Mozilla Thunderbird folder if there is one.

Do Not remove any profile folders.

After rebooting the computer, run a registry scanner if you have one. Then run the installer. +++++++++++++++++++++++++++ If there is a problem, start your Computer in safe mode and try again.

http://encyclopedia2.thefreedictionary.com/Linux+Safe+Mode This shows how to Start all Computers in Safe Mode; Free Online Encyclopedia

Please note, registry cleaners are not recommended. They fix no problems, the registry should not be messed with unless under direct supervision of a professional, and registry "cleaners" are usually just malware that cause more problems than they pretend to "solve".

Please uninstall Ashampoo and any other "registry cleaners", don't install then again, and install Malwarebytes (www.malwarebytes.com) to scan for malware on your computer

Thank you for your replies Fred and Tyler. The answer I am really looking for is to the following question . What purpose does those "missing" Mozilla Firefox exe files that are shown in the report perform ? The program "Firefox" runs without error, it is up to date of a few days ago. Are these "missing files" possibly leftovers from updates? If so does the update Author need to know.

No. Those "errors" are made up. They aren't really errors. They are pretend issues to make you feel good about running a "registry cleaner".