Start Firefox in Safe Mode to check if one of the extensions (orange Firefox button, top left corner (The image "new fx menu" does not exist. for v29+)/Tools > Add-ons > Extensions) is causing the problem (switch to the DEFAULT theme: orange Firefox button, top left corner (The image "new fx menu" does not exist. for v29+)/Tools > Add-ons > Appearance).

• Do not click the Reset button on the Safe mode start window or otherwise make changes.

• Windows/Mac: Go to Help > Restart with add-ons disabled
• Linux: Run firefox -safe-mode in the Terminal/Konsole

You can check for problems with the places.sqlite database file in the Firefox profile folder.

• http://kb.mozillazine.org/Bookmarks_history_and_toolbar_buttons_not_working_-_Firefox
• https://support.mozilla.org/kb/Bookmarks+not+saved#w_fix-the-bookmarks-file

• Places Maintenance: https://addons.mozilla.org/firefox/addon/places-maintenance/