Hi lonamel, Thank you for using Firefox. There is a a work around that was used in the last version. If you open the task manager on the Windows Start menu you can close the process that is already running.

This is one of the known issues: https://bugzilla.mozilla.org/show_bug.cgi?id=966469 and https://bugzilla.mozilla.org/show_bug.cgi?id=985655

Also I think it was clear history on shutdown, do you have this preference selected?

I apologize for the inconvenience while we look for a solution to this issue.

Hi,

Thank you for your response. Actually this problem does not solve with closing firefox in task manager.

The firefox shows it is closed totally, I cannot find it in task manager window. It happens when I opens firefox, use it, than close...and than it don't want to open again. It's not connected to deleting history - I know firefox stops there always, but after clearing history, I can open. Also, it's not the preference to clear history every time, I do it manually.

It seem so be a different, new issue.

Ok let's also make sure that you do not have a parent.lock file in you profile folder: http://kb.mozillazine.org/Profile_in_use or that it is not a general Firefox profile issue.

Can you please try a small experiment: Click the 3 bar menu then click the question mark. Then click "Restart Firefox without add ons" Does this issue occur after you close Firefox and try to open it again?

One more experiment: Start firefox with the profile manager and create a new profile (uncheck the do not use on start when you first use it so you can easily switch back to the other profile the next time you start Firefox. ) Profilvezérlő használata firefox profilok eltávolításához, és létrehozásához

The other thought is if it does not want to open again, is there a window open somewhere already.