Recent answers to On opening a new window tab shows - "browser.startup.homepage=about:home"https://support.mozilla.org/en-US/questions/9762522013-11-03T00:11:55-07:00You can check for problems with preferences and rename or delete the prefs.js file and possible numb2013-11-03T00:11:55-07:00cor-elhttps://support.mozilla.org/en-US/questions/976252#answer-496925<p>You can check for problems with preferences and rename or delete the prefs.js file and possible numbered prefs-##.js and user.js files to reset all prefs to the default value.
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<ul><li><a href="http://kb.mozillazine.org/Preferences_not_saved" rel="nofollow">http://kb.mozillazine.org/Preferences_not_saved</a>
</li><li><a href="http://kb.mozillazine.org/Resetting_preferences" rel="nofollow">http://kb.mozillazine.org/Resetting_preferences</a>
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<p>Start Firefox in <u><a href="/en-US/kb/diagnose-firefox-issues-using-troubleshoot-mode" rel="nofollow">Safe Mode</a></u> to check if one of the extensions (Firefox/Firefox/Tools &gt; Add-ons &gt; Extensions) or if hardware acceleration is causing the problem (switch to the DEFAULT theme: Firefox/Firefox/Tools &gt; Add-ons &gt; Appearance).
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<ul><li>Do NOT click the Reset button on the Safe Mode start window.
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<ul><li><a href="https://support.mozilla.org/kb/Safe+Mode" rel="nofollow">https://support.mozilla.org/kb/Safe+Mode</a>
</li><li><a href="https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes" rel="nofollow">https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes</a>
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