Please provide the full names of the files quarantined.

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 the profiles folder.

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

idallasj said

ClamXAV is reporting: /Applications/Firefox.app/Contents/Info: Trojan.OSX.Flashback FOUND Live Infections Found: 1 /Applications/Firefox.app/Contents/Info: Trojan.OSX.Flashback FOUND Live Infections Found: 1 in Firefox 59.0.1. Should I be concerned? When I quarantine/delete the flagged file(s), Firefox will not start.

Only issue with malware concerns I have seen in last years was if Mac users downloaded Firefox 58.0.1 from the third-party MacUpdate site instead of from mozilla.org like www.mozilla.org/firefox/all/

Some applications posted on MacUpdate including 58.0.1 for a time had hacked links for a short time that sent users a version of Firefox 58.0.1 with a crypto minor tool.

On occasions some antivirus clients to have had a false positive with a new Firefox version whether by download or a update and the FP be fixed in a definitions update in antivirus client.