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Firefox won't open because it says another application of Firefox is already runnin.

  • 8 replies
  • 6 have this problem
  • 1 view
  • Last reply by cor-el

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Quite often when I try to open Firefox it say I have to shut down another application of Firefox that is already running. There is no other application running, and the only way to open Firefox is to reboot my computer.

Quite often when I try to open Firefox it say I have to shut down another application of Firefox that is already running. There is no other application running, and the only way to open Firefox is to reboot my computer.

All Replies (8)

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You say you have to reboot your computer. I can offer a little assistance, having had the problem myself. I do not know what goes on or why, but if you right click the task bar at the bottom and go into the "Processes" Tab on Task Manager, you can highlight "Firefox.exe" and click the "End Process" button. Then you can click on your Firefox icon and it will open Firefox without you having to reboot your computer. I hope this is of some use at least until someone proposes a complete fix.

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Use Ctrl-Alt-Del and open the Task Manager. Under the Processes tab, single click Firefox.exe to highlight it and then click the End Process tab. This will stop Firefox that is running in the background.

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thanks both - I will wait till it happens again before saying it worked.

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Why don't you install the add-on Close Button 0.4.0 found at https://addons.mozilla.org/en-US/firefox/addon/close-button/?src=api which adds an exit button to the toolbar. I know this works with Firefox 8.0 and 9.0.1

Clicking on the cross closes all instances of Firefox at once including the plugin-container and download window.

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See "Hang at exit":

See "Firefox hangs when you quit it":

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when I right click taskbar, I have 3 tabs under properties

taskbar start menu toolbar

before I put in last update I know I used to get a rectangular box that was easy to find what I was looking for and get rid of a running program, but not so now.

Nowhere can I find *processes*

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Did you check the "Hang" articles?
If it happens after you've run and closed Firefox and can't reopen Firefox then those articles apply.


Check the Processes tab in the Task Manager (XP: Ctrl+Alt+Del, Vista: Shift+Ctrl+ESC) to see if there are hanging Firefox processes.
If you see any firefox.exe process on the Processes tab then click the End process button to end those Firefox processes.