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 to us!

Ok, that definitely cleared EVERYTHING.  :) Lots of clean up after doing that.

Facebook works normally now. I think the issue was the "oldbar" extension. After the reset, I began fixing the settings and testing Facebook each time and nothing was going wrong. But when I began to add extensions back in, that's when Facebook crashed again.

When you check for updates on some extensions, it will tell you that they are up to date because, well, nobody updated it. But if someone else creates a newer version that works with the newer Firefox versions, then people just begin using the new one, and forget about the old one. I think this happened to oldbar. It was incompatible but nobody knew, or at least didn't tell anyone.

I installed another version called "old location bar". That one didn't affect Facebook at this point. If anyone is still using "old bar", remove it and use "old location bar" instead.

Thank you for the fix.