See [http://forums.mozillazine.org/viewtopic.php?f=38&t=1979591] Start Firefox in <u>[[Safe Mode|Safe Mode]]</u> to check if one of the extensions (Firefox/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem (switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance). *Do NOT click the Reset button on the Safe Mode start window. *https://support.mozilla.org/kb/Safe+Mode *https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes You can open the <b>about:config</b> page via the location bar and search for prefs that refer to <b>superfish</b> and reset user set (bold) <b>superfish</b> prefs via the right-click context menu to the default value. If you do not keep changes after a restart or otherwise have problems with preferences, see: *http://kb.mozillazine.org/Preferences_not_saved