Have you tried doing a clean reinstall?

To do a clean reinstall of Firefox, please follow these steps: Note: You might want to print these steps or view them in another browser.

1. Download the latest Desktop version of Firefox from mozilla.org (or choose the download for your operating system and language from this page) and save the setup file to your computer.
2. After the download finishes, close all Firefox windows (or open the Firefox menu and click the close button ).
3. Delete the Firefox installation folder, which is located in one of these locations, by default:
   • Windows:
     • C:\Program Files\Mozilla Firefox
     • C:\Program Files (x86)\Mozilla Firefox
   • Mac: Delete Firefox from the Applications folder.
   • Linux: If you installed Firefox with the distro-based package manager, you should use the same way to uninstall it - see Install Firefox on Linux. If you downloaded and installed the binary package from the Firefox download page, simply remove the folder firefox in your home directory.
4. Now, go ahead and reinstall Firefox:
   1. Double-click the downloaded installation file and go through the steps of the installation wizard.
   2. Once the wizard is finished, choose to directly open Firefox after clicking the Finish button.

More information about reinstalling Firefox can be found here.

WARNING: Do not use a third party uninstaller as part of this process. Doing so could permanently delete your Firefox profile data, including but not limited to, extensions, cache, cookies, bookmarks, personal settings and saved passwords. These cannot be easily recovered unless they have been backed up to an external device! See Back up and restore information in Firefox profiles.

Please report back to say if this helped you!

Thank you.

As noted in my original post, I have already tried the clean reinstall several times.

Sorry, it was not clear whether it was a clean or normal reinstall. This points to a corrupt profile, which won't be solved by a reinstall. Please try creating a new profile , and starting Firefox with that new profile. If this works, you can recover your data from the old profile.

Please report back to say if this helped you!

That worked! Thank you!

I am not able to get back to the ProfileManager screen to delete the old profile. I tried the "run" command again but now just get the Firefox screen. Is ProfileManager a choice somewhere?

Thank you!!!

If the Profile Manager window does not appear, you may need to include the full path to the Firefox program, enclose that line in quotes, then add a space followed by -P. Examples: Firefox (32-bit) on 64-bit Windows

"C:\Program Files (x86)\Mozilla Firefox\firefox.exe" -P Firefox (32-bit) on 32-bit Windows (or the new 64-bit Firefox on 64-bit Windows)

"C:\Program Files\Mozilla Firefox\firefox.exe" -P

If the Profile Manager window still does not open, Firefox may have been running in the background, even though it was not visible. Close all instances of Firefox or restart the computer and then try again.

Thank you!