Recent answers to when I open Firefox, I get following message, "Java Script Application Type Error: Components. classes (cid) is undefined. What's wrong?https://support.mozilla.org/en-US/questions/8558612011-07-29T17:55:57-07:00This issue can be caused by an AVG extension.
Start Firefox in Diagnose Firefox issues using Trouble2011-07-29T17:55:57-07:00cor-elhttps://support.mozilla.org/en-US/questions/855861#answer-222915<p>This issue can be caused by an AVG extension.
</p><p>Start Firefox in <u><a href="/en-US/kb/diagnose-firefox-issues-using-troubleshoot-mode" rel="nofollow">Diagnose Firefox issues using Troubleshoot Mode</a></u> to check if one of the extensions is causing the problem (switch to the DEFAULT theme: Firefox (Tools) &gt; Add-ons &gt; Appearance/Themes).
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<ul><li>Don't make any changes on the Safe mode start window.
</li><li><a href="https://support.mozilla.com/kb/Safe+Mode" rel="nofollow">https://support.mozilla.com/kb/Safe+Mode</a>
</li></ul>
<ul><li><a href="https://support.mozilla.com/kb/Troubleshooting+extensions+and+themes" rel="nofollow">https://support.mozilla.com/kb/Troubleshooting+extensions+and+themes</a>
</li></ul>