[Work] firefox, mozilla locked!

In Firefox 1.5 or later, a "Close Firefox" dialog box may appear with one of these messages:
"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."

How to unlock your profile

Your profile may be inaccessible for a number of reasons, most often because the application failed to shut down completely the last time it was used and the task or process is still "running in the background", even though there are no open application windows. Ending the running process is normally sufficient to unlock the profile. If the profile remains inaccessible, try these other solutions:
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End processes

Go through your task or process list to see if multiple instances of Firefox, Thunderbird or Mozilla Suite are still running or not responding and end each instance found.
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Remove the profile lock file
The application may have shut down abnormally, leaving the lock in place. To fix this, open the profile folder and delete the file,

* "parent.lock" (Windows),
* "lock" and ".parentlock" (Linux), or
* ".parentlock" (Mac OS X)