Start '''[https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-using-safe-mode Firefox in Safe Mode]''' {web Link} by holding down the '''<Shift><br> ''(Mac Options)'' ''' key, and then starting Firefox. Is the problem still there? ------------------------------- Separate Issue; Your System Details shows; Installed Plug-ins Shockwave Flash 15.0 r0 Shockwave Flash 18.0 r0 Version 0.9.19, Copyright 2006-2012 Veetle Inchttp://www.veetle.com/ Version 0.9.18, copyright 2006-2010 Veetle Inchttp://www.veetle.com/ <br>Having more than one version of a program may cause issues. You must remove the older programs. Then get the current full installer. Flash: Grab the uninstaller from here: '''[http://helpx.adobe.com/flash-player/kb/uninstall-flash-player-windows.html Uninstall Flash Player | Windows]''' '''[http://helpx.adobe.com/flash-player/kb/uninstall-flash-player-mac-os.html Uninstall Flash Player | Mac]''' Then reinstall the latest version. Flash Player '''Version 18.0.0.232<br>https://www.adobe.com/products/flashplayer/distribution3.html''' '''Note: Windows users''' must download the “Internet Explorer” '''and''' “Plugin-based browsers” installers.

Current Firefox versions keep a maximum number of visited page and do not have a time limit for the history. Firefox determines automatically how many pages can be kept without affecting the performance. You can see the current value of this maximum as the value of the read-only pref places.history.expiration.transient_current_max_pages on the about:config page. It is possible that you exceed this maximum if history get deleted. See Marco Bonardo's blog about this subject: * http://blog.bonardo.net/2010/01/20/places-got-async-expiration