Recent answers to Mac shutdown will not complete if Firefox has been opened since boothttps://support.mozilla.org/en-US/questions/6900182010-06-04T07:21:52-07:00Plugins also can cause Firefox to hang.
See Troubleshoot issues with plugins like Flash or Java to f2010-06-04T07:21:52-07:00cor-elhttps://support.mozilla.org/en-US/questions/690018#answer-17096<p>Plugins also can cause Firefox to hang.
See <a href="/en-US/kb/troubleshoot-issues-with-plugins-fix-problems" rel="nofollow">Troubleshoot issues with plugins like Flash or Java to fix common Firefox problems</a>
</p><p>See also <a href="/en-US/kb/firefox-hangs-or-not-responding" rel="nofollow">Firefox hangs or is not responding - How to fix</a> (Hang at exit)
</p>First, try upgrading Firefox to the latest version, 3.6.3. See How to download and install Firefox 2010-06-04T05:43:10-07:00zzxchttps://support.mozilla.org/en-US/questions/690018#answer-17097<p>First, try upgrading Firefox to the latest version, 3.6.3. See <a href="/en-US/kb/how-download-and-install-firefox-mac" rel="nofollow">How to download and install Firefox on Mac</a> for details.
</p><p>If it still happens, see if quitting Firefox before shutting down fixes it. Go to the Firefox menu and choose Quit.
</p><p>If it still happens after updating to 3.6.3 and after quitting, check the Activity Monitor after quitting Firefox to see if "firefox" or "firefox-bin" is still listed. The activity monitor is located in /Applications/Utilities. In this case, let me know if it's still there after quitting.
</p>Extensions can sometimes be the cause of problems. If the problem does not occur in Safe Mode, then 2010-06-04T05:41:06-07:00Chris_Iliashttps://support.mozilla.org/en-US/questions/690018#answer-17098<p>Extensions can sometimes be the cause of problems. If the problem does not occur in Safe Mode, then you can disable your extensions one-by-one until you find out which one is causing the problem. See <a href="/en-US/kb/troubleshoot-extensions-themes-to-fix-problems" rel="nofollow">Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems</a>
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