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 followed the instructions (1) close Firefox completely, (2) open the Firefox profile folder, and (3) delete or rename all files named "places.sqlite" . I also renamed "permissions.sqlite". There was no "places.sqlite-journal" or "places.sqlite.corrupt".

Upon restarting Firefox these two files were rebuilt, but the problems are still there. Nothing has changed.

Start Firefox in Diagnose Firefox issues using Troubleshoot Mode to check if one of the add-ons is causing the problem (switch to the DEFAULT theme: Tools > Add-ons > Appearance/Themes).

• Don't make any changes on the Safe mode start window.

See:

• Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems

This corrected the problem, as I had several extensions that were incompatible with Firefox 4.0. For others attempting to follow these instructions, I did encounter one difficulty. The Add-ons manager would not open unless I had at least two tabs already open.

Many thanks for your help in correcting this aggravation.

You're welcome