For an unknown reason, Firefox 3.5 crashed on me in Ubuntu 9.10. When I tried restarting it, a dialog popped up which read:
“Firefox is already running, but is not responding. To open a new window, you must first close the existing Firefox process, or restart your system.”
Neither of these suggestions worked for me. I even deleted all the Firefox packages on my computer, and reinstalled. I got the same dialog box when I opened my freshly installed Firefox.
I worked some Google magic, and found a help page for this problem on support.mozilla.com. It turns out that my Firefox profile directory (which wasn’t deleted when I removed Firefox) has a lock file that is supposed to be removed when Firefox starts. If the lock file exists when you try starting Firefox, you get the aforementioned dialog box.
Mozilla provides a number of different solutions for this, I chose simply to delete my default profile, and create a new one. I chose this because I had a new installation of firefox, and I didn’t have any important data to retain. If you want to restore your original profile, you should go here. Otherwise, follow these directions for deleting and creating your profile.
In a terminal, type
$ /usr/bin/firefox -ProfileManager
where /usr/bin/firefox is the path to your firefox installation. The Profile Manager will appear (provided Firefox is closed), and you can go from there.
