First, is the button completely gray? If it's completely gray, the link probably launched in a separate tab or window. If the arrow on the button is black, could you right-click it? Sometimes a page uses a script to modify history, and this can add extra entries to the Back button. Using the right-click tab history list allows you to skip back to an earlier page in those cases. But if that's the problem, it seems unlikely to be a normal behavior on so many sites. Perhaps there is a glitch with one of your add-ons. Could you test in Firefox's Safe Mode? In Safe Mode, Firefox temporarily deactivates extensions, hardware acceleration, and some other advanced features to help you assess whether these are causing the problem. ''If Firefox is not running:'' Hold down the Shift key when starting Firefox. ''If Firefox is running:'' You can restart Firefox in Safe Mode using either: * "3-bar" menu button > "?" button > Restart with Add-ons Disabled * Help menu > Restart with Add-ons Disabled and OK the restart. ''Both scenarios:'' A small dialog should appear. Click "Start in Safe Mode" (''not'' Refresh). Any improvement? (More info: [[Troubleshoot Firefox issues using Safe Mode]])

See also: *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