Applications Data/Thunderbird/Profiles/abozowue.default = that's for Thunderbird and isn't related to your problem with Firefox

Have you tried restarting your PC?

You mean that you have two Firefox installations- one portable and one desktop. Just try uninstalling Firefox from both USB and computer along with any history, addons( be sure to backup history and addons), then reinstall Firefox. That should resolve the issue. About your "parent.lock" file, that file is used by both Firefox and Thunderbird, so if you have both Firefox and Thunderbird installed, there will be two SEPARATE copies. The file which you are refering to belongs to Thunderbird.

Dozens of times. Several times a day.

Thanks for that pertinent information.

I will try again once I reboot without Thunderbird started.

However, that would mean that Explorer cannot find the Firefox parent.lock file.

So, since I have no Firefox parent.lock file, that Explorer can find, how can I solve the problem?

I may have neglected to say that I can start Firefox from the USB stick. I just cannot run it on my main machine.

And, I greatly prefer it to the competition internet browsers!

L

I should also add that I have uninstalled and reinstalled Firefox 3.6 on the main machine, but it had no effect on the problem.

Firefox will start from the USB stick, but when it does there is a 'Starting Firefox' window that persists even when the program loads and is operative.

To get rid of it, I can right click on the program window on the bottom line of the browser, and tell it to 'end program', which it will do after a moment or so, with no effect on the Firefox session running from the USB stick.

With Thunderbird closed, searching the entire set of hard drives on the machine with Explorer finds no parent.lock file.

However, when I try to start Firefox, I get the same window with the message:

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.

So, what Firefox process could still be running after a reinstall and many reboots?

It seems to me that there may be some unintended cross link between the Firefox on the USB stick and the one on the computer, so that both profiles were showing up on the main machine. So, when I thought that I was deleting one, it persisted and now blocks Firefox from starting on the main machine.

Ideally, the two Firefox installations should be entirely separate, and indeed if you try to start Ff from the USB stick while a session is running on the main machine, I was told that I would be alerted to close down the latter.

However, it seems that some code got crossed somehow.

I am OK with running Firefox Portable from the USB stick on my main home machine and others at work, which do not have Ff installed.

However, I would really like to get my old Ff up and working again on the main home machine.

It's my bedtime down under here in the Land of Oz, so hopefully when I get going again in eight hours or so, someone will have provided a solution to my little problem.

Thanks in advance.

Havng slept on the problem with the new clues obtained last night, I went to my Documents and Settings/Application Data.

There was no Firefox folder at that level, but there was one for Mozilla that contained one. However, nowwhere under it was there a parent.lock file. Nor was there a profile.

So, starting with the Mozilla folder itself, I renamed it.

Firefox then started normally, and a new Mozilla folder had been created.

I then copied the old Extentions-BackupByFirefox folder into the new Mozilla folder, and again no problem with starting Firefox.

When I deleted one of the two profiles back when I was running the USB stick, I must have picked the one that held my main machine profile.

So, all I have to do now is to recreate my old profile, which should not be too onerous a task, as it was not all that complex.

Thanks for the tips.

crissman,

I'm glad that you were able to fix this problem. Please mark this thread as Solved.