Do you close Firefox yourself or let you Windows close Firefox when you shutdown Windows?

A shutdown would require to close Firefox. A hibernate could possibly be done with keeping Firefox running and in that case you should still have all open tabs if you wake up Windows.

Are you using "Clear history when Firefox closes" to clear any personal data?

I always close all open programs before shutting down my laptop and usually also on hibernate.

I lose the pinned tabs after closing FF for either type of shutdown, but not if I hibernate with it open.

On closing clear history clears only the cache, no other history or cookies.

Does Firefox create a new sessionstore.js file?

Note that clearing the cache can take a lot more extra time, so make sure to give Firefox enough time to close completely before you shutdown the computer. You can check in the Windows Task Manager how long it takes for the Firefox process to disappear.

I have a system widget on my desktop that allows me to see when the cpu gets done working after closing FF and when the memory drops off before I shut things down for the day.

I've never checked for a sessionstore.js file. I'll do that next time. Will that be in appdata with my profile, or under mozilla in program files?

It will be in the Firefox profile folder.

You can use this button to go to the current Firefox profile folder:

• Help > Troubleshooting Information > Profile Directory: Show Folder (Linux: Open Directory; Mac: Show in Finder)
• http://kb.mozillazine.org/Profile_folder_-_Firefox

The sessionstore.js file in the profile folder is used to store session data, but is only present when Firefox is closed.

You can find these files in the sessionstore-backups folder:

previous.js (cleanBackup: copy of sessionstore.js from previous session that was loaded successfully)
recovery.js (latest version of the sessionstore written during runtime)
recovery.bak (previous version of the sessionstore written during runtime)
upgrade.js-<build_id> (backup created during an upgrade of Firefox)

You can copy a file from the sessionstore-backups folder to the main profile and rename the file to sessionstore.js to replace the current file (make a backup copy of the current sessionstore.js).

See also: http://www.ghacks.net/2014/06/27/mozilla-launches-improved-session-restore-firefox-33/

Thanks for the ghacks link (I wandered off on some Microsoft Win 10 shenanigans) and the sessionstore file info. Armed with this I will monitor my browser behavior more closely to see why it is doing what it does with my tabs.

Thanks for all the help.

You're welcome