Hi chris.meister12, sorry to hear about this problem. A BEX error typically refers to an illegal memory access that triggers Windows to kill a program. But it's difficult to know the exact root cause of such errors when both the application and module name are firefox.exe.

A Firefox 78.0.1 update will be released soon and if that doesn't help, you could try some tests along these lines:

(A) Start Firefox in its Safe Mode to rule out add-on issues (steps at the end)

(B) Start Windows in "Safe mode with networking" to see whether Firefox runs better -- this bypasses numerous programs that start automatically

(C) File a bug and let the developers advise on what kinds of logs would be helpful

For (A):

In its Safe Mode, Firefox temporarily deactivates extensions, hardware acceleration, any userChrome.css/userContent.css files, and some other advanced features to help you assess whether these are causing the problem.

If Firefox is not running: Hold down the Shift key when starting Firefox. (On Mac, hold down the option/alt key instead of the Shift key.)

If Firefox is running: You can restart Firefox in Safe Mode using either:

• "3-bar" menu button > "?" Help button > Restart with Add-ons Disabled
• (menu bar) Help menu > Restart with Add-ons Disabled

and OK the restart.

Both scenarios: A small dialog should appear. Click "Start in Safe Mode" (not Refresh).

Any improvement?

Hello,

Yes I can start Firefox while Firefox is in Safe Mode, and while my Computer is in Safe Mode.

Anything I should try next ?

Thanks.

It could be the work of one of your add-ons, or it could be Hardware Acceleration.
How to disable Hardware Acceleration {web link}

Type about:addons<enter> in the address bar to open your Add-ons Manager.
Hot key; <Control> (Mac=<Command>) <Shift> A)

In the Add-ons Manager, on the left, select Extensions. Disable a few add-ons, then Restart Firefox.

Some added toolbar and anti-virus add-ons are known to cause Firefox issues. Disable All Of them.

If the problem continues, disable some more (restarting FF). Continue until the problem is gone. After, you know what group is causing the issue. Re-enable the last group ONE AT A TIME (restarting FF) until the problem returns.

Once you think you found the problem, disable that and re-enable all the others, then restart again.

Let us know who the suspect is, detective.

BEX errors also have been associated with malware, so you can also do a malware scan.

Do a malware check with several malware scanning programs on the Windows computer.

• https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-caused-malware

Please scan with all programs because each program detects different malware. All these programs have free versions.

Make sure you update each program to get the latest version of their databases before doing a scan.

• Malwarebytes' Anti-Malware:
  https://www.malwarebytes.com/
• AdwCleaner:
  https://www.bleepingcomputer.com/download/adwcleaner/
  https://www.softpedia.com/get/Antivirus/Removal-Tools/AdwCleaner.shtml
• SuperAntispyware:
  https://www.superantispyware.com/
• Microsoft Safety Scanner:
  https://www.microsoft.com/security/scanner/en-us/default.aspx
• Windows Defender:
  https://windows.microsoft.com/en-us/windows/using-defender
• Spybot Search & Destroy:
  https://www.safer-networking.org/en/index.html
• Kasperky Free Security Scan:
  https://www.kaspersky.com/security-scan

You can also do a check for a rootkit infection with TDSSKiller.

• Anti-rootkit utility TDSSKiller:
  https://support.kaspersky.com/viruses/disinfection/5350

https://support.kaspersky.com/viruses/utility

Thanks it looks like the Hardware Acceleration was the issue !

Problem solved !

Glad to help. Safe Surfing.