What did you try from the other thread?

If you did not try a Reset already, you could try this lesser step:

Sometimes the file that stores toolbar layout becomes corrupted. You can rename the file and customize from scratch.

Open your current Firefox settings (AKA Firefox profile) folder using either

• "3-bar" menu button > "?" button > Troubleshooting Information
• (menu bar) Help > Troubleshooting Information

In the first table on the page, click the "Show Folder" button

Leaving that window open, switch back to Firefox and Exit, either:

• "3-bar" menu button > "power" button
• (menu bar) File > Exit

Pause while Firefox finishes its cleanup, then rename localstore.rdf to something like localstore.old

Start Firefox back up again. Any improvement in function of the UI?

In case there was some damage to files in your Firefox program folder, or incompatible files brought forward that were not cleared by the update, could you try:

Clean Reinstall

A regular reinstall may leave some stray files in your programs folder. This method is a bit cleaner.

(1) If needed, download a fresh installer for Firefox 31 from https://www.mozilla.org/firefox/all/ to a convenient location. (Scroll down to your preferred language.)

(2) Exit out of Firefox.

(3) Rename the folder

C:\Program Files (x86)\Mozilla Firefox

to

C:\Program Files (x86)\OldFirefox

(4) Run the installer you downloaded in #1. It should automatically connect to your existing settings.

Does Firefox behave more normally?

Note: Some plugins may exist only in that OldFirefox folder. If something essential is missing, look in these folders:

• C:\Program Files (x86)\OldFirefox\Plugins
• C:\Program Files (x86)\OldFirefox\browser\plugins