Please look at this article, if you have not already done so

• "Firefox is already running but is not responding" error - How to fix

The first thing to try is killing the Firefox process (and for that matter any plugin-container). You should kill the process before trying to delete the lockfile.

If all that fails then as suggested in the article you will need to create a new profile and migrate data.

• Profile Manager - Create, remove or switch Firefox profiles_creating-a-profile
• http://kb.mozillazine.org/Moving_your_profile_folder#Create_a_new_profile_and_migrate_your_old_data

Boot the computer in Windows Safe Mode with network support (press F8 on the boot screen) as a test to see if this helps.

• http://www.bleepingcomputer.com/tutorials/how-to-start-windows-in-safe-mode/

Do you meet the requirements for the current Firefox release?

• http://www.mozilla.org/en-US/firefox/28.0/system-requirements/

Thanks - the process isn't running as I haven't *ever* been able to start Firefox. Fresh from boot I can't delete the lockfile - even though there *is no Firefox process running*

I don't have any data or profile to migrate as this is a brand new install of Firefox on a machine that has never had it before. This error happened immediately after the installer finished - Firefox has *never* run on this box.

Thanks for the suggestions.

Booting in safe mode will be awkward as this is a VM I connect to via RDP.

As I mentioned in my question it's Windows 2008, so it should meet the requirements.

Do you have any utilities to identify the process that has its grips on parent.lock? You may be able to use Process Explorer: http://technet.microsoft.com/en-us/sysinternals/bb896653.aspx

Try to delete the Profiles folder or the Firefox\Profiles and the profiles.ini files to force Firefox to create a new default profile.

• http://kb.mozillazine.org/Profile_folder_-_Firefox

• C:\Users\<user>\AppData\Roaming\Mozilla\Firefox\Profiles\<profile>\

Note that the "AppData" folder in Windows Vista and later Window 7+ versions and the "Application Data" folder in XP/Win2K are hidden folders.

• http://kb.mozillazine.org/Show_hidden_files_and_folders

Weirdly, leaving it a day and reconnecting to the server via rdp again allowed me to delete the lockfile, and indeed the profiles folder.

I'm still getting the same error though. There is *no* Firefox process running. There is *no* Profile folder or lockfile.

I even deleted the profiles.ini file as it pointed to the non-existent profile.

Any more suggestions anyone?

It's fixed.

I uninstalled. I deleted the AppData/Roaming/Mozilla and AppData/Local/Mozilla folders, then I reinstalled (this time running the installer as administrator instead of running direct from the browser as the install instructions said).

It worked.

I suspect it was a security policy issue preventing access to the lockfile properly.

Thanks for the suggestions everyone.

edit

I missed the post above. Partly no doubt the annoying lag on forum listings updates.

Is the entry in the profiles.ini file sane and does it point at a location that has suitable read and write permissions. I am of course assuming if you rename profiles.ini in its current location that Firefox does recreate it.

• http://kb.mozillazine.org/Profiles.ini_file

Presumably after you delete or rename the profile folder Firefox does manage to recreate and populate the profile.

If this is not happening do a clean reinstall of Firefox again, deleting all the Firefox program folders and files prior to the install.

• Troubleshoot and diagnose Firefox problems_5-reinstall-firefox

John99 - no, nothing was recreated after I attempted to run again, but as I said, uninstalling and reinstalling as administrator fixed this.Thanks anyway.