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multiple instances of firefox running cannot kill in task manager "Access denied"

or_rain
or_rain
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There's no issue with starting a new instance after closing one, the "firefox is already running" error is not occurring (ok maybe once or twice a month, but it's not related to this problem, as my problem happens all the time.) Apparently when closing a ff window it never fully stops. My computer slows down because of it and these multiple instances of firefox show up in Task Manager. When I try to kill the extra processes it just goes "BANG" and the "access denied" error dialog box appears. They are all running under my user account, and in CPU some are just 10 or 25 and some are in the hundreds and some are over a million. what the heck is going on? I'm running Windows 7 64 bit and ff 23.0 but this has been happening since about ff 15 (?)

There's no issue with starting a new instance after closing one, the "firefox is already running" error is not occurring (ok maybe once or twice a month, but it's not related to this problem, as my problem happens all the time.) Apparently when closing a ff window it never fully stops. My computer slows down because of it and these multiple instances of firefox show up in Task Manager. When I try to kill the extra processes it just goes "BANG" and the "access denied" error dialog box appears. They are all running under my user account, and in CPU some are just 10 or 25 and some are in the hundreds and some are over a million. what the heck is going on? I'm running Windows 7 64 bit and ff 23.0 but this has been happening since about ff 15 (?)

All Replies (1)

Wesley Branton
Wesley Branton
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When closing Firefox completely, it is important to close it using the Exit button, located inside of the Firefox/File menu.

Another cause to this problem could be a Firefox preloader. Do you have any programs that will load Firefox automatically? They are supposed to improve start time.

You can also try Firefox Safe Mode to see if the problem goes away. Safe Mode is a troubleshooting mode, which disables most add-ons.

(If you're not using it, switch to the Default theme.)

  • Open the Help menu and click on the Restart with Add-ons Disabled... menu item while Firefox is running.

Once you get the pop-up, just select "'Start in Safe Mode"

If the issue is not present in Firefox Safe Mode, your problem is probably caused by an extension, and you need to figure out which one. Please follow the Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems article for that.

To exit the Firefox Safe Mode, just close Firefox and wait a few seconds before opening Firefox for normal use again.

I hope that one of my solutions helps to fix your problem. Please report back with updates soon.

NOTE: You are using an outdated version of Firefox. This can cause security and functionality issue. Please update to the most recent version as soon as possible.