The throbber keeps loading?

See - Websites show a spinning wheel and never finish loading

I've gone through what you suggested and continue to have the same problem. I can get gmail and facebook to load, but when I try to log in, the spinning wheel pops up.

Can you try in safe mode, it may be caused by hardware acceleration and or a addon.

• Diagnose Firefox issues using Troubleshoot Mode

It is possible that your security software (firewall, anti-virus) blocks or restricts Firefox or the plugin-container process without informing you, possibly after detecting changes (update) to the Firefox program.

Remove all rules for Firefox and the plugin-container from the permissions list in the firewall and let your firewall ask again for permission to get full unrestricted access to internet for Firefox and the plugin-container process and the updater process.

See:

• https://support.mozilla.org/kb/Server+not+found
• https://support.mozilla.org/kb/Firewalls

• https://support.mozilla.org/kb/fix-problems-connecting-websites-after-updating

I've gone through the reset process and the box saying that it's been reset never appears.

If so you need to test in a new profile.

• refer to theProfile Manager - Create, remove or switch Firefox profiles article.