Hi, Does this happen when another screensaver is set? You may want to check this behavior with a built-in screensaver that came with the OS. If it doesn't repeat with another OS screensaver you can report the problem [http://www.dreamaquarium.com/forum/viewforum.php?f=2&sid=5e6cd2eaabb4c75d75ed97fe220e64b2 here.] ............................................................................................................................... Useful links: [https://support.mozilla.com/en-US/kb/Options%20window All about Tools > Options] [http://kb.mozillazine.org/About:config Going beyond Tools > Options - about:config] [http://kb.mozillazine.org/About:config_entries about:config Entries] [https://addons.mozilla.org/en-US/firefox/addon/whats-that-preference/ What's That Preference? add-on] - Quickly decode about:config entries - After installation, go inside about:config, right-click any preference, enable (tick) MozillaZine Results to Panel and again right-click a pref and choose MozillaZine Reference to begin with. [https://support.mozilla.com/en-US/kb/Keyboard%20shortcuts Keyboard Shortcuts] [https://support.mozilla.com/en-US/kb/Viewing%20video%20in%20Firefox%20without%20a%20plugin Viewing video in Firefox without a plugin] [http://kb.mozillazine.org/Profile_folder_-_Firefox Firefox Profile Folder & Files] [https://support.mozilla.com/en-US/kb/Safe%20Mode Safe Mode] [https://support.mozilla.com/en-US/kb/Basic%20Troubleshooting Basic Troubleshooting] [http://kb.mozillazine.org/Problematic_extensions Problematic Extensions] [https://support.mozilla.com/en-US/kb/Troubleshooting%20extensions%20and%20themes Troubleshooting Extensions and Themes] [http://kb.mozillazine.org/Testing_plugins Testing Plugins] [https://support.mozilla.com/en-US/kb/Troubleshooting%20plugins Troubleshooting Plugins]