Let’s do a full clean re-install;

Note: Firefox comes in three or more folders on all computers. They are;

Maintenance: (Programs Folder) <Windows Only> Firefox itself: (Programs Folder) And two folders in the profile of each user on the computer for each Firefox profile for that user.

If you remove the Firefox folder, the user profiles would not be affected.

Download Firefox For All languages And Systems {web link}

Firefox ESR; Extended Support Release {web link}

Beta, Developer, Nightly versions https://www.mozilla.org/en-US/firefox/channel/desktop/

Install Older Version Of Firefox {web link} Be sure to read everything here.

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) Note: Check Both Folders

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.

How to Start all Computers in Safe Mode; {web link} Free Online Encyclopedia

This did not work the first time EXCEPT I failed to remove the x86 folder. I did that this time around and Firefox is back to functioning as expected. Many thanks for the quick reply and for the help! I've gotten so I depend upon Firefox and DuckDuckGo. (Now time to install the VPN!)

Glad to help. Safe Surfing.

Okay, the problem is popping up again. And worse. I've gone through re-install per the step-by-step directions given. Firefox worked normally for a few sessions, then tanked (failed to come-up) again. I've been through, troubleshooting mode (which, of course, blew my DuckDuckGo extension out of the water and I had to add it back), and more. The only way I can get Firefox to come up for sure is to reboot. After rebooting (Windows 11) Firefox will come up once. If I try to open a new tab/URL, I get the +New tab but the tab never opens. If I click on a URL in, for example, an email, sometimes Firefox will open, most of the time it won't. As I said, I am using the DuckDuckGo extension. Could that be the problem? I'm using Webroot for Internet and other protection. Could that be the problem? This is maddening. Something is interfering with Firefox coming up but I don't know what. The only way I can guarantee, other than rebooting, that I can use Firefox is to bring up my home page after rebooting and then not close the browser. Quite honestly I'm about at the point I'm going to switch to Edge because Firefox has become so unreliable (and I've been using Firefox for years and telling others to dump other browsers on Windows and use Firefox).

I just thought: could something be getting into the cache that's causing this?

One way to find out. Location of the cache/cache2 folder; Windows: *C:\Users\<user>\AppData\Local\Mozilla\Firefox\Profiles\<profile>\ Mac: ~/Library/Caches/Firefox/Profiles/ Linux: ~/.cache/mozilla/firefox/

Close Firefox. Open your file browser to the above and remove the folder.

If that does not help, let's try this;

Many have reported issues using the 64bit Firefox. Install the 32bit version from; Download Firefox For All languages And Systems {web link}

A post was flagged as Solved Problem. If the problem is not solved, please remove that flag. If you don’t, others that can help may not read this post.

Go to that message, and use the Undo link to its right.

Finally, installing the 32-bit version seems to have fixed the problem. I can consistently get Firefox to come up. I had to export my bookmarks from the 64-bit version (once I got it up via Edge) and add DuckDuckGo back, but that is trivial.

Thank you for the help!

Rich

Hello,

I am glad to hear that your problem has been resolved. If you haven't already, please select the answer that solves the problem. This will help other users with similar problems find the solution.

Thank you for contacting Mozilla Support.

What security software do you have?

Cor-el: as said earlier what worked was installing the 32-bit version. In fact, I just realized when I recently updated Firefox I apparently updated to the 64-bit version and that’s when my problems began.

As to security software, I’m using WebRoot. I have yet to install a VPN. My bad!