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

• Don't make any changes on the Safe mode start window.
• https://support.mozilla.com/kb/Safe+Mode

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

In Firefox 4 you can use one of these to start in Safe mode:

• Help > Restart with Add-ons Disabled
• Hold down the Shift key while double clicking the Firefox desktop shortcut (Windows)

This can also be caused by 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

Corel: You keep posting this all over the place but can't you see it isn't helping people? Safe Mode is useless. I have no conflicts with add-ons, extensions or plugins. Those dozens of "places" files that you say must be deleted...that's utterly insane. Firefox has created a new browser that is buggy in a major league way and they must fix it. If not, I'm going to use another browser and I will uninstall Firefox.

Try going to about:config and change browser.sessionhistory.max_entries 0 to browser.sessionhistory.max_entries 999

mercave's suggestion solved this problem for me. thank you.