Mac shutdown will not complete if Firefox has been opened since boot
Shutdown command clears my desktop, but the spinning bars appear ad infinitum, and my G5 has to be powered off. I was using only three applications: iTunes, Safari, and Firefox. Through testing, I have determined that the problem doesn't occur after I have opened Safari by itself, or iTunes by itself. Shutdown hangs only after I have opened Firefox.
This happened
Every time Firefox opened
== Every time I tried to shutdown my G5 in the past three days.
Alle svar (3)
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 Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems
First, try upgrading Firefox to the latest version, 3.6.3. See How to download and install Firefox on Mac for details.
If it still happens, see if quitting Firefox before shutting down fixes it. Go to the Firefox menu and choose Quit.
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.
Plugins also can cause Firefox to hang. See Troubleshoot issues with plugins like Flash or Java to fix common Firefox problems
See also Firefox hangs or is not responding - How to fix (Hang at exit)