Firefox v55 has been giving users problems. I suggest you install v54 until the problems are fixed. https://support.mozilla.org/en-US/kb/install-older-version-of-firefox?cache=no Be sure to read everything here. If you still want to downgrade, look under; '''I still want to downgrade. ''' Click the '''Directory of other versions and languages''' link. Look for the directory of the version that you want. But, remember that '''old versions may have security issues. ''' You should also check out Firefox; Extended Support Release https://www.mozilla.org/en-US/firefox/organizations/ https://www.mozilla.org/en-US/firefox/organizations/notes/ https://www.mozilla.org/en-US/firefox/organizations/system-requirements/ ------------------------- Let’s do a full clean re-install; Download using the instructions above. 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 ++++++++++++++++++++++++++++ '''Do Not''' remove the profiles folder. Look for, and rename any '''Mozilla''' or '''Firefox''' program folders by adding .old to them. Do not rename the '''Mozilla Thunderbird''' folder if there is one. After rebooting the computer, run a registry scanner if you have one. Then run the installer. If all goes well, remove the OLD folders when you are done. +++++++++++++++++++++++++++ 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