The following comes from Ticket 20060123114442.
From John Shipman:
I had a firefox running on pi.nmt.edu, and it died uncleanly.
Now, when I try to run firefox from pi, I get this popup:
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.
Normally if I have more than one firefox running, I get the
Choose User Profilepopup so I can create a new profile to coexist with the other firefox processes.
On pi, I did a ps -Al, but it didn't show a firefox process.
I was able to fix this once before by removing my ENTIRE .mozilla directory and all subdirectories. This is a bit drastic, because I had to re-enter all my preferences.
Is there some way to defeat this interlock, short of removing the whole .mozilla directory?
The first effort at cure would be to delete the .parentlock file found under /.mozilla/firefox/profilename/ (where profilename is a jumble of letters and numbers).
This doesn't always work though. What you may find is that the message (above) is not displayed nor does a firefox window ever appear.
Another way to coax firefox to launch is with the command
firefox -ProfileManager and then create or use a new profile.
Yet another way (perhaps in some way equivalent to the last one) is to open profiles.ini and set the IsRelative tag to 0 then firefox should start normally and create a new user file.