''(Edit: found a screenshot in a duplicate thread: [[/questions/1057654]])'' ---- You can open the <b>about:config</b> page via the location/address bar and search for prefs that refer to <b>quick_start</b>. You can reset user set (bold) prefs via the right-click context menu to the default value. ---- You can use the SearchReset extension to reset some preferences to the default values. *https://addons.mozilla.org/firefox/addon/searchreset/ Note that the SearchReset extension only runs once and then uninstalls automatically, so it won't show on the "Firefox > Add-ons" page (about:addons). ---- Note that this is a message form an extension (quick_start should give a clue, possibly Fast Start) that isn't working properly or there are things leftover after uninstalling this extension. 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