Firefox will not open - it says it has a copy open already - and it does not. This happened after I tried to update to new firefox.

Question

I attempted to upload the new version of Firefox. When I did this - I could not open Firefox at all - a box pops up telling me to '''Close Firefox - a copy of firefox is already open - Only one copy of Firefox can be open at a time.''
I tried to remove Firefox completely form the computer and reinstall - and I get the same message.
I am using a macbook prop with Lion operating system

Answer 1

Must be the "hang at exit" problem. You already know how to do Step1; now just determine which Add-on (Extension or Plugin) is causing the problem.<br /><br />
#Stop the Firefox process:
#*[http://kb.mozillazine.org/Kill_application Mozillazine - Kill application]
#*Windows 7 users click [http://www.techrepublic.com/blog/window-on-windows/reap-the-benefits-of-windows-7s-task-manager/2576 here]
#Why Firefox may hang:
#*[http://support.mozilla.com/en-US/kb/Firefox+hangs Firefox hangs] (see Hang at exit)
#*[http://kb.mozillazine.org/Firefox_hangs Firefox hangs (Mozillazine)] (see Hang at exit and Closing Firefox properly)
#*[https://support.mozilla.com/en-US/kb/Firefox+is+already+running+but+is+not+responding Firefox is already running but is not responding]
#Use Firefox Safe Mode to find a problem with an Extension or Plugin:
#*Don't check anything when entering Safe Mode, just continue
#*If the problem does not occur in Safe Mode it is probably and Extension or Plugin causing the problem
#*See:
#**[[Safe Mode]] and [http://kb.mozillazine.org/Safe_Mode Safe Mode (Mozillazine)]
#**[http://support.mozilla.com/en-US/kb/Troubleshooting+extensions+and+themes Troubleshooting extensions and themes]
#**[http://support.mozilla.com/en-US/kb/Troubleshooting+plugins Troubleshooting plugins]
#**[http://support.mozilla.com/en-US/kb/Basic+Troubleshooting Basic Troubleshooting]
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