Try couple of cycles of closing down and reopening with Firefox in its safe mode does that help ?

• Diagnose Firefox issues using Troubleshoot Mode

Pressing & holding down the Shift Key whilst starting Firefox is one method of starting in safemode.

Do you set Firefox to clear History at closedown ? If so set that back to its default and repeat as above did that help.

• That is the opposite setting of Delete browsing, search and download history on Firefox_how-do-i-make-firefox-clear-my-history-automatically

Note when closing down for now give Firefox at least 10 minutes before trying to kill or power off. Even longer if you can still see disk activity. If Firefox runs into problems trying to closedown it should timeout, and then start trying to generate and submit a crash report.

• See Firefox crashes - asking for support

If you visit about:crashes do you see recent crash reports ? If so please paste in couple of the Crash IDs starting with bp-

Use one of these to close Firefox if you are currently doing that by clicking the close X on the Firefox title bar.

• "3-bar" menu button > Exit (Power button)
• Windows: File > Exit
• Mac: Firefox > Quit Firefox
• Linux: File > Quit

If you use "Clear history when Firefox closes" then try to disable this feature.

• Options/Preferences > Privacy > Firefox will: "Use custom settings for history": [X] "Clear history when Firefox closes"

the exit command did the trick, I'll remember that in the future. I never had that "erase history upon exit" setting on.