Uninstall Flash 25.0 r0 and new one using : https://askubuntu.com/questions/815294/how-should-i-uninstall-remove-adobe-flash-player-in-ubuntu Reinstall : Flash Player Version: 27.0.0.187 Current Version https://get.adobe.com/flashplayer/otherversions/ Step 1: Select Operating System Step 2: Select A Version (Firefox, . . . .) Note: Other software is offered in the download. <Windows Only>

There are errors in Video Card Drivers, may want to reinstall or update.

Please : https://support.mozilla.org/en-US/kb/export-firefox-bookmarks-to-backup-or-transfer and https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles then https://support.mozilla.org/en-US/kb/refresh-firefox-reset-add-ons-and-settings TEST....... If no issues then Extensions which need to be added back in 1 at a time and tested ..... Or it is your Profile : Make a new one and test ...: https://support.mozilla.org/en-US/kb/profile-manager-create-and-remove-firefox-profiles

Please let us know if this solved your issue or if need further assistance.

Does Firefox seem to remember closed tabs in real time? To re-open a closed tab you can try either:

• right-click a tab in the same window > undo closed tab
• History > Recently Closed Tabs

Normally Firefox will retain session history unless one of the following clears it:

• private windows (either on demand or automatic)
• Firefox is set to clear history at shutdown
• a privacy-related extension
• an external cleaning or privacy program

To check the first two:

• Linux: "3-bar" menu button (or Edit menu) > Preferences
• Mac: "3-bar" menu button (or Firefox menu) > Preferences
• Windows: "3-bar" menu button (or Tools menu) > Options
• Any system: type or paste about:preferences into the address bar and press Enter/Return to load it

In the left column, click Privacy & Security. On the right side, if the page says:

• Firefox will: Remember history => no problem

• Firefox will: Use custom settings for history => make sure there isn't a checkmark for either:
  • "Always use private browsing mode"
  • "Clear history when Firefox closes"

• Firefox will: Never remember history => no session history is saved, to disable this, select Use custom settings and uncheck the "Always use private browsing mode" box

You can view, disable, and often remove unwanted or unknown extensions on the Add-ons page. Either:

• Ctrl+Shift+a (Mac: Command+Shift+a)
• "3-bar" menu button (or Tools menu) > Add-ons
• type or paste about:addons in the address bar and press Enter/Return

In the left column of the Add-ons page, click Extensions. Then cast a critical eye over the list on the right side. Any system extensions that Firefox installs on its own are hidden from this page, so everything listed here is your choice (and your responsibility) to manage. Anything that might remove history? If in doubt, disable.

I had to change preferences by unchecking Browsing And Download History in Settings for Clearing History. That is quite different to version 56 for which I am able to clear browsing history and still open with all tabs from the previous session. That may be because I use the add-on TabMixPlus session manager with version 56.

Thanks for the replies.

Thank you for reporting back. Your theory is likely correct.