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When I start mozilla firefox web browser, sometimes I see a message saying that "a Mozilla Firefox is already running, please close it or restart your program", while I don't have one running at that time. What is the problem?

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  • 28 have this problem
  • Last reply by cor-el

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When I start mozilla firefox web browser, sometimes I see a message saying that "a Mozilla Firefox is already running, please close it or restart your system". As a matter of fact, there is no firefox browser running at that time. Since I cannot do anything about it, I have to restart my computer before I can use the web browser, which bothers me dearly. What is the problem?

All Replies (4)

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Plug-in and tasks started by Firefox may continue after attempting to close Firefox. The "X" in the upper right-hand corner closes the Window (same as Ctrl+Shift+W) but even if it is the last Firefox window, it does not necessarily close Firefox .

The only proper way to exit Firefox is to use Exit through the File menu, not the "X" in the upper right corner of last Firefox window. Menus hidden: then use Alt+F then X.

Firefox hangs | Troubleshooting | Firefox Support (some extensions cause a problem)

Use the Windows Task Manger to remove all running firefox.exe in the "Processes" tab of the Windows Task Manager, then restart Firefox.

"Restartless Restart" extension for Firefox 4.0 only (2 KB download )

use to close and restart Firefox after enabling or disabling an extension, switching to a new theme, or modifying configuration files, then you don't have to worry about delay or have to look in the Task Manager to see if Firefox is closed yet. Uses keyboard shortcut "Ctrl+Alt+R" or a file menu option.

Windows 7 users can use Ctrl+Shift+Esc to get to the Windows Task Manager quicker than starting with Ctrl+Alt+Del.

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I just posted a question about this too, do you multiple users on the machine? My PC is on a domain, and if one account is logged in with Firefox open, the others can't start it.

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I'm having no luck with any of the above. I have Windows 7 and Firefox 12, and this just started a week or so ago. I get the " already running " error message if I want to restart Firefox after closing down. I've disabled all the add-ons and extensions and have only default theme running. It won't restart in safe mode at all. When I try that nothing happens, and I can find the firefox.exe*32 process running in Task Manager. The only thing that works is to right click on the bar at the bottom and select Task Manager there, then delete the process.

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Please start a new thread for your problem or question and provide troubleshooting information like your operating system and installed extensions and installed plugins.

Use "Firefox/File > Exit" (Mac: "Firefox > Quit"; Linux: "File > Quit") to close Firefox if you are currently doing that by clicking the close X on the title bar.

See also: