We're sorry that you are experiencing some issues while setting up Firefox.

Has Firefox ever been installed on this computer previously?

The Reset Firefox feature can fix many issues by restoring Firefox to its factory default state while saving your essential information.
Note: This will cause you to lose any Extensions, Open websites, and some Preferences.

To Reset Firefox do the following:

1. Go to Firefox > Help > Troubleshooting Information.
2. Click the "Reset Firefox" button.
3. Firefox will close and reset. After Firefox is done, it will show a window with the information that is imported. Click Finish.
4. Firefox will open with all factory defaults applied.

Further information can be found in the Refresh Firefox - reset add-ons and settings article.

Did this fix your problems? Please report back soon.

Did you download Firefox from the official Mozilla website or an external source?

Yes. I downloaded from the official site. I've had FF for years but have not wanted to upgrade because every time I do ... this happens.

Please try to install an older version of Firefox from here.

If it installs and runs, you can then try updating to the most recent version of Firefox, via the Help > About Firefox.

Please report back soon.

I have done this and it works, but again when i update the problem reoccurs

Please check out this support article.

Also, you can post a bug report on Bugzilla if you wish.