Make sure that the Location Bar is not set to "Nothing":
Edit > Preferences > Privacy > Location Bar: When using the location bar, suggest: History,Bookmarks,History and Bookmarks

See Smart Location Bar

cor-el: Thanks for the post. Your suggestion worked fine, so the problem is solved.

Regards, Doug

I tried that and it doesn't work. I have Mac OX v 10.6.4 . Anyone have a clue? It's very frustrating. thanks.

This can be a problem with the file places.sqlite that stores the bookmarks and the history.

• http://kb.mozillazine.org/Bookmarks_history_and_toolbar_buttons_not_working_-_Firefox

I had this problem very recently with a firefox update. For those of you who might have the same issue, cor-el's solution works but with a slight modification. On my version of firefox (13.0.1), the steps are as follows:

1) Press 'alt,' go to 'Tools' on the upper bar.

2) Select 'Options' on the drop-down menu

3) Select 'Privacy'

4) Near the bottom, under the section 'Location bar,' select 'History and Bookmarks.'