Hey Doug, I don't even have FF installed .
I have use FF in the past & I have no problem with people that like it.
We all have browser preferences for what ever reason.
To me it seems like you got an infected download of FF.
I would do a through uninstall of FF .
If you have "System Restore" on turn it off .
Reboot into Normal mode & then shutdown & boot into safe mode.
From safe mode do a complete scan with your Anti-virus & MalwareBytes.
Clean whatever is detected (Unless you know something detected is a "false positive") .
Reboot into normal. Turn "System Restore" back on if you use it .
Download a fresh copy of FF .
Do A right click scan of the FF.exe with Avast & MalwareBytes.
On a side note I've seen the FF version "PaleMoon" recommended here on the forum . I haven't tried it but I understand it is a lot like FF.
If you use "System Restore" you could try Ibex's suggestion .
I never had much success with it but I guess for some people it works OK. I try to keep a current backup with Acronis & use that instead.
I keep "System Restore" turned off " .