Sorry to hear about the crashes. Our support article also describes how to find submitted crash report numbers on disk if necessary (for Windows 10):

If you can't open Firefox at all (even in Safe Mode):

Find the text file for your latest submitted crash report using these steps:

1. Click the Search button in the taskbar.
2. In the search box, type %APPDATA%\Mozilla\Firefox\Crash Reports\submitted\ and press Enter.

Use the View menu to arrange the files by date and open the newest file.

Source: Firefox crashes - asking for support

Two external programs that often cause startup crashes are:

• Websense Endpoint Protection, security software typically used in a business environment
• Trusteer Rapport, security software recommended/required by some banks

If you know you are running either of these programs, we can suggest general steps to address compatibility problems.

Thanks so much for your reply. Was able to get to the crash reports. This is the crash report number: Crash ID: bp-5ee613fd-0deb-4331-b59e-a8a402160323 I am not running either of the security softwares you mentioned.

Thank you for the crash report. If you click through to the crash report and click the "Modules" tab, you'll see that the first on the list is "FLVSrvLib.dll". That module installs with various Applian Technologies programs including Freecorder and Replay Media Catcher.

This crash is closely associated with having BOTH the Applian software AND Norton security software, or in rare cases Kaspersky security software. Since presumably you don't want to switch away from Norton/Kaspersky, you can remove or deactivate the Applian software as follows:

(1) Uninstall & reboot

If you have either of those programs and it isn't essential, try uninstalling it and then restarting Windows to ensure that none of its components are left running.

Will Firefox start normally after that?

(2) Prevent auto-startup

If you prefer not to uninstall the program, a few other users said using the msconfig program to prevent FlvSrvc.exe from running at startup bypassed the problem.

See: http://windows.microsoft.com/en-us/windows/using-system-configuration

You still may need to reboot to unload the software from your current Windows session.

Success?

The report also shows modules from Trusteer Rapport, but those might be from a perfectly compatible version, so let's tackle one issue at a time.

I uninstalled Freecorder and tried opening Firefox before I even rebooted. It seems to be running just fine. You're a genius! Thank you so much for your help!