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I am being told that "Firefox is still running but not responding;" I have follow the guide to fix this problem and even re-installed Firefox, but it persists

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So in the past I have gotten the "Firefox is already running, but is not responding. The old Firefox process must be closed to open a new window" message and I have used Task Manager to fix the problem, but today even after stopping the process via Task Manager, I kept getting the same error message. I even uninstalled Firefox and then reinstalled it and got the same message. My Firefox account works fine on my other devices. It only happens on my Dell laptop, which is running Windows 10. Any suggestions? Thanks!

So in the past I have gotten the "Firefox is already running, but is not responding. The old Firefox process must be closed to open a new window" message and I have used Task Manager to fix the problem, but today even after stopping the process via Task Manager, I kept getting the same error message. I even uninstalled Firefox and then reinstalled it and got the same message. My Firefox account works fine on my other devices. It only happens on my Dell laptop, which is running Windows 10. Any suggestions? Thanks!

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It sounds like your default Firefox profile may be corrupt. Your profile contains all of your user settings and data. You will need to try creating a new profile using the profile manager.

For more information on using the profile manger to create a new profile, please refer to this Mozilla support article:

If you are able to run Firefox from this new profile, then set it as the default. You can then recover some of your data from your old profile. To do so, please refer to this Mozilla support article:

Note: Although it is possible to copy addons and their data into the new profile, it is not recommended, as you could risk copying corrupt files into your new profile.