I disabled all of my extensions and then enabled them one by one. I found the culprit. Foxit PDF Creator Toolbar 3.13.1.100008 was the problem. I removed this addon and everything works fine now.

I don't have Foxit PDF Creator Toolbar but was having the same problem after installing F 8.0. I disabled half my extensions and the problem was fixed so I knew the problem was in the half that had been disabled. If the problem hadn't been fixed, I would have known the problem was in the other half. Continuing this half technique, I was able to find the problem. In my case, it was Ask Toolbar 3.13.1.1000007 that was the problem.

Tab Utilities 1.1.2 causes the same problems on Firefox 10+

(Tab Mixer Plus works... I've been bouncing between the two as one or the other belches.)

I couldn`t get anything from my address bar, then i started disabling some exts. and it works fine now. Just go to your extensions and start disabling them, one by one, you will solve this problem.

I corrected this (new) problem after a lot of searching. I am running AVG antivirus and apparently consented to AVG Safe Search to be added as an extension. Once I disabled it and restarted Firefox (Tools/Add Ons/Extensions), it returned to working normally. As much as I would like to use Safe Search, I will just leave it off until a solution is worked out.