With Firefox 41 (and higher), it's no longer possible to customize the page shown in a new tab via changing the preference browser.newtab.url in about.config. Because of the fact that hijackers abused the preference in the past, Mozilla decided to remove it (see bug 1118285). Fortunately, by removing it, Mozilla also introduced a new API to bring this functionality back to life as an add-on. This add-on allows the user to choose a certain page in a new tab. New Tab Override (browser.newtab.url replacement) https://addons.mozilla.org/en-US/firefox/addon/new-tab-override/ This is also available using '''[https://addons.mozilla.org/en-US/firefox/addon/classicthemerestorer/ Classic Theme Restorer (Customize Australis)]''' {web link} Restore squared tabs, appmenu, add-ons bar, small button view and more on Australis UI (Windows/MacOSX/Linux + Fx 29+). -------------------- Separate Security Issue: Update your Flash Player '''Note: Windows users''' should download the '''ActiveX''' for ''Internet Explorer.'' '''and''' the '''plugin''' for ''Plugin-based browsers'' (like Firefox). '''Note: Windows 8 and Windows 10''' have built-in flash players and Adobe will cause a conflict. Install the plugin only. Not the ActiveX. Flash Player Version: '''25.0.0.148''' https://get.adobe.com/flashplayer/ Direct link scans current system and browser '''Note: Other software''' is offered in the download. <Windows Only> https://get.adobe.com/flashplayer/otherversions/ Step 1: Select Operating System Step 2: Select A Version (Firefox, Win IE . . . .) '''Note: Other software''' is offered in the download. <Windows Only> +++++++++++++++++++ See if there are updates for your graphics drivers https://support.mozilla.org/en-US/kb/upgrade-graphics-drivers-use-hardware-acceleration