Computer Help and Support

Did you reinstalling it from scratch and make sure you have the latest version? If you had the option to install an earlier version, that could cause problems. Or, maybe the latest one has some quirks on your system.

Since you reset everything, could it be some Windows setting that's causing the problem? Or do you have another security program running-- Windows Defender is good enough for most things and often won't play nice with other security stuff.

If you try another browser and the same thing happens, it's obviously not Firefox.

FWIW, when I upgraded FF to this latest and greatest one, it's faster and seems more stable, but lost some of the goodies on the older one. Same thing happened when I upgraded Opera. I'm starting to use Vivaldi, which is a lot like the old Opera and really nice to work with.

And, you did note that the Mozilla help page said you might be compromised? While resetting, is there any chance you picked up some nasties? A Malwarebytes scan might find something.