Gah-Your-tab-just-crashed https://support.mozilla.org/en-US/kb/firefox-crashes-troubleshoot-prevent-and-get-help

FredMcd, I have done everything that was suggested at the url you posted. No clue.

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) 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.

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

Did all that except PC safemode. Didn't work. I then reloaded Firefox back level 64.02 This crashes same way except it gives a crash report. Submitted https://crash-stats.mozilla.com/report/index/f03ab991-aa4e-4eac-8efa-d9cb10190207

Product Firefox Release Channel release Version 64.0.2 Build ID 20190108160530 (2019-01-08) OS Windows 8 OS Version 6.2.9200

bp-f03ab991-aa4e-4eac-8efa-d9cb10190207 Signature: jsimd_idct_islow_avx2

Uptime 3 seconds

Crash Reason EXCEPTION_ILLEGAL_INSTRUCTION

mbae.dll = Malwarebytes Anti-Exploit

This is for Sumo's Related Bugs 1520760 REOPENED --- crash on jsimd_idct_islow_avx2

Update Malwarebytes. If the problem continues, disable it.

Disabled latest Malwarebytes and 64.0.2 still crashes and now does not give crash report. 65 crashes also.

Start Firefox in Safe Mode {web link}

A small dialog should appear. Click Start In Safe Mode (not Refresh). Is the problem still there?

Start your Computer in safe mode with network support. Then start Firefox. Try Secure websites. Is the problem still there?

http://encyclopedia2.thefreedictionary.com/Linux+Safe+Mode Starting Any Computer In Safe Mode; Free Online Encyclopedia

Tried Windows Safe mode and both 64.0.2 and 65 worked. Restarted with no safe / regular load and they both still worked. Thanks. Sorry I didn't try it a couple days ago. Explanation? Reason?

It could have been a corrupt file that was overwritten.

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 more easily.

Thank you for contacting Mozilla Support.