moz-extension://{UUID} type links are used for extensions to handle their pages, so it looks that you have an extension installed that modifies the homepage setting. You can check "Options/Preferences -> Home" to see whether that mentions the involved extension and decide if you want to keep it. *https://support.mozilla.org/en-US/kb/how-to-set-the-home-page Start Firefox in <b>Safe Mode</b> to check if one of the extensions ("3-bar" menu button or Tools -> Add-ons -> Extensions) or if <b>hardware acceleration</b> or <b>userChrome.css</b> is causing the problem. *switch to the DEFAULT theme: "3-bar" menu button or Tools -> Add-ons -> Themes *do NOT click the "Refresh Firefox" button on the Safe Mode start window *https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-using-safe-mode *https://support.mozilla.org/en-US/kb/troubleshoot-extensions-themes-to-fix-problems ----- See also: *https://support.mozilla.org/en-US/kb/use-troubleshooting-information-page-fix-firefox