Kill application

To completely quit (exit) a Mozilla application (Firefox, Thunderbird, Mozilla Suite, etc) you should do the following.

1. In each application window, click "File -> Exit"
2. Close all remaining dialog boxes and secondary windows such as the Downloads window and the Extensions window.
3. Ensure QuickLaunch is closed: in Windows, look in your System Tray (the area next to the clock) for your Mozilla application's icons. If present, right-click on them and choose "Exit".

Sometimes, even after following the steps above, the application may still be running ‘in the background’. This can cause problems such as a “profile in use” error. In such cases you should terminate the application's running processes in another way, depending on your operating system.

Windows

Use the Task Manager:

• Windows Vista: "Ctrl+Shift+Esc" -> "Processes" (or right-click the Taskbar and select "Task Manager -> Processes")
• Windows XP: "Ctrl+Alt+Delete" -> "Processes" (or right-click the Taskbar and select "Task Manager -> Processes")
• Windows NT/2000: "Ctrl+Alt+Delete" -> "Task Manager -> Processes".
• Windows 95/98/ME: "Ctrl+Alt+Delete".

In the list of running processes, look for "firefox.exe", "thunderbird.exe", "mozilla.exe" or "seamonkey.exe" (whichever applies) and terminate, if found. Note that multiple instances may exist so you should carefully check through the processes list and end each one.

Linux

Use the "ps" and "kill" commands. (See their respective manual pages with "man ps" and "man kill" and various other documentation online.)

Mac OS X

Go to your Apple Menu and select "Force Quit". For Mac OS X 10.3 and later, you can also use the Activity Monitor found in your "Utilities" folder ("Applications -> Utilities -> Activity Monitor").