I did not have this problem when updating on Windows 7 Home Premium 64bit or Windows 7 Professional 32bit, but I did have this problem on 2 Windows 2008R2 terminal servers in my cloud hosted environment. I upgraded those servers last night and all users in the office are complaining. I've tried resetting firefox, clearing all history, deleting my profile and creating a new one and starting Firefox in safe mode. Nothing has worked. The only other thing I can think of to try is to uninstall Firefox and install a fresh copy, but I can't do that until after business hours. Troubleshooting steps in the past suggest going to about:config as a first step, but I can't because the location bar (address bar) doesn't work. I even tried creating a simple html page with a link to about:config, but that doesn't work either.

Thank you for your comments. We had to roll back to 19.0.2.

Mozilla is working on it.

https://bugzilla.mozilla.org/show_bug.cgi?id=857672