Firefox not working?
February 7th, 2020
Try ending the process in task manager and opening the program again.
If you’ve done that, and it didn’t help, delete the user profile or completely delete the application data folder.
Funnily enough I’ve had that happen twice now with Opera. The same thing as your explaining, was running in the task manager at something or other. I had to unistall it and reinstall it, loosing all my feeds and email settings. Now I just back up all the data in the application data and local settings, and hopefully if it happens again that will sort it. I’d go with what the poster above suggests, as I don’t use FireFox. Strange how it happens to both browsers though