That's severe. Have you tried shutting down and restarting Windows since this problem began? Could you check for a malware issue: * [[Uninstall BitGuard to fix crashes with Firefox]] * [[Troubleshoot Firefox issues caused by malware]] ---- Firefox 27 is now available. I think that might not help, but you can get it here if you want to try it: https://www.mozilla.org/firefox/all/ No need to uninstall Firefox 26 before installing Firefox 27.