Search Support

Avoid support scams. We will never ask you to call or text a phone number or share personal information. Please report suspicious activity using the “Report Abuse” option.

Learn More

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."

  • 9 replies
  • 22 have this problem
  • 183 views
  • Last reply by spaarks

more options

I keep getting the message "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."

I have tried uninstalling and reinstalling. Deleting and reinstalling. Installing on a different drive, etc. It was working fine, then one day, that is all it will say. I'd tried making sure the folder isn't read only. I've also looked for the parental lock folder to delete (and shown hidden files), but it does not exist on any installation that I've done. Running out of solutions aside from the idea that maybe firefox is just broken.

I've also scanned for malware (malwarebytes), spyware (spybot) and done virus scans (AVG Free 2015).

Had a similar problem with IE, but have gotten it fixed by uninstalling and using windows update to update step by painful step from 9 to 11, and remaking my stupid icon.

Windows 7 SP1 Ultimate with all updates. Very nice hardware (but still a slow boot), which makes me still suspect malware of some type, or maybe AVG deleting something important.

I keep getting the message "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." I have tried uninstalling and reinstalling. Deleting and reinstalling. Installing on a different drive, etc. It was working fine, then one day, that is all it will say. I'd tried making sure the folder isn't read only. I've also looked for the parental lock folder to delete (and shown hidden files), but it does not exist on any installation that I've done. Running out of solutions aside from the idea that maybe firefox is just broken. I've also scanned for malware (malwarebytes), spyware (spybot) and done virus scans (AVG Free 2015). Had a similar problem with IE, but have gotten it fixed by uninstalling and using windows update to update step by painful step from 9 to 11, and remaking my stupid icon. Windows 7 SP1 Ultimate with all updates. Very nice hardware (but still a slow boot), which makes me still suspect malware of some type, or maybe AVG deleting something important.

All Replies (9)

more options

From what I have been reading from other posts on this forum, the issue may be caused by the clear history settings. It was suppose to have been fixed in v30.

Type about:preferences <Enter> in the address bar.

Select Privacy.

The button next to History, select Use Custom Settings.

At the bottom of the page, turn on Clear History When Firefox Closes. At the far right, press the Settings button. Turn on ONLY Cache and Form And Search History leaving the others off.

This is not a cure but will make it easier if Firefox locks up in Windows. https://support.mozilla.org/questions/997866 {web link}

more options

The next time you get that message, STOP ! ! Do you have a quick launch icon for Firefox? If so, right click and select Open New Window. Sometimes this works. Then Menu > File > Exit

more options

I apologize, I feel I need to clarify.

Firefox is not running. I open it to get it to run (open new window is not an option I have). Before it starts running or pops up, the aforementioned error message appears.

I have tried windows task manager, but no other versions of firefox are running, except when the error message is up.

more options

In other words, no fixes that require firefox to run or be open can be used. That is the problem, it will not run, but says it is running, even though it is not according to the task manager.

more options

Do you have the Firefox icon on your quick launch? Right click on it, and select Open New Window. Sometimes this works. If it opens, close it by Menu > File > Exit.

more options

Go to the Mozilla Add-ons Web Page {web link} (There’s a lot of good stuff here) and search for an add-on that will put a close/quit button icon on the toolbar.

more options

I do not have that option.

That seems like it's not actually fixing the problem, and I have to add on more stuff to fix a program that is not working.

Nor does it explain why firefox worked fine, with the same version, two weeks ago.

more options

The add-on is not a fix, its a convenience.

more options

Thunderbird is already running, but is not responding. To open a new window, you must first close the existing Thunderbird process, or restart your system. If it is already running why can't I see it? I do not have firefox or any other browser running.