Why does firefox "close" when I close the window but the process doesn't shutdown even with the upgrades since problem was reported.since i had updated to FF25

Question

Frequently after I have been viewing numerous sites on firefox, when I close down the last window and try to reopen firefox, I am told that the program is already running and needs to be shut down. Using Task Manager is not useful, since task manager doesn't show the program as up and running. The only way to get the program to close so it can be used for a different subject is to reboot the computer. This is happening 10 - 12 times a week now, and gradually getting worse. This closes out everything I have open, making it necessary to save all opened files BEFORE I reboot, and then going back to reopen all of them. None of the other questions I've seem point to this particular quirk in the problem.

Answer 1

This is not a cure but will make it easier if Firefox locks up.
'''https://support.mozilla.org/questions/997866''' {web link}
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.
Press the '''Alt''' or '''F10''' key to bring up the tool bar.
Followed by;
Windows; '''Tools > Options'''
Linux; '''Edit > Preferences'''
Mac; ''application name'' '''> Preferences'''
Then '''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.