There are a few possible causes for that error, for details see "Firefox is already running but is not responding" error - How to fix.

did everything listed under this help file and still not working

Create a new profile as a test to check if your current profile is causing the problems.
See Basic Troubleshooting: Make a new profile
There may be extensions and plugins installed by default in a new profile, so check that in "Tools > Add-ons > Extensions & Plugins"

If that new profile works then you can transfer some files from the old profile to that new profile (be careful not to copy corrupted files)
See http://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Firefox

i just want to uninstall firefox, i can use firefox on another profile but even setting the other account as admin i still cant uninstall.........thats all i want to be able to remove it why cant i?????????????????????

In windows XP one way is to you use

start -> control panel -> add or remove programmes

You will need to use an account with administrator privileges. I assume the firefox program must not be in use when you try this, you should be able to stop the process with task manager.

In XP:

1. Ctrl+Alt+Del keys all pressed together will get you the task manager,
2. use the process tab, and
3. then click on the images column look for 'firefox.exe'
4. right click it and then use
5. 'end process'

been there done that, dosnt work.......clicked on remove and nothing happens, went into the program and clicked on uninstall in the firefox folder, nothing happens.......and i am running my laptop as admin all the time.

and it dosnt show up in the taskmaniger eather under prosseses

Make sure that the profile with default=1 in profiles.ini is pointing to an existing profile folder.

You can delete profiles.ini to force Firefox to create a new default profile.

See http://kb.mozillazine.org/Recovering_a_missing_profile

there we go deleting profiles.ini worked yay!!!!

This problem was the reason I dumped FF late in 2009. I loaded the latest (well the Beta) version of FF last week and it does exactly the same - meaning I have to shut down and restart. I can get that sort of nonsense with IE8 so once once more I dumped FF a browser I used to love. Chrome here I come until you play up once more.

Please don't tell me I should go reset this or that as I am a definite Non Geek and want it to work out of the box. I am fed up of being mocked by Mac users.

Hello,

  Not certain what all this jazz is about a profile file?. I love Firefox- yet have been having serious issues after the last two updates- perhaps I can go back to older copies somehow. The problem is Firefox is stuck in memory- it refuses to clear after you shut it down.  Go to task manager under processes (not applications- it won't show there) look for a real memory hog- one using the most memory- it will probably say "firefox.exe", shut it down in task manager.  Now you can restart Firefox.