see this links:

Tab preferences and settings

How do I restore my tabs from last time?

The two links are references on how the feature is SUPPOSED to work. They do not address the PROBLEM.

The problem is that FF does not restore previous tabs when the user is someone other than 'administrator'.

Did you use Private Browsing last time?

I wasn't aware of Private Browsing option.

I checked and it is not enabled.

In case you are using "Clear history when Firefox closes":

• do not clear Browsing History

• Tools > Options > Privacy: History: [X] Clear history when Firefox closes > Settings
• https://support.mozilla.org/kb/Clear+Recent+History

Note that clearing "Site Preferences" clears all exceptions for cookies, images, pop-up windows, software installation, and passwords.

Have you noticed this behaviour with any other Option settings?

I'm not using "Clear history when Firefox closes".

>> Have you noticed this behaviour with any other Option settings?

I haven't noticed any other settings not working (this is a new, to me, laptop and I only just started using FF on it).

If I change my home page using the 'Options' dialog, exit FF and then start up FF my tabs are gone but the new value for my home page has been saved as expected so it is at least saving some option preferences.

What does the setting just above the Home Page textbox say?

"When Firefox starts:"...

When Firefox starts: Show my windows and tabs from last time

If I change this setting it will be reflected in the new FF session if I exit and restart FF.

Thanks for that. What I was trying to eliminate was some variant of something that happened to me, where I'd get different behaviour (in my case on updates) depending on whether I was logged in as admin or as a user. I thought something odd with profiles might have been happening. In that case, your "When Firefox Starts:" setting would have reset each time.

So just to clarify your original question-detail. There are two ways to escalate an account's privileges: 1) To go into user account settings as admin and change the account-type to admin, or 2) to select "Run as admin" when starting an application.

Which one of those have you tried? What was the result?

>> Which one of those have you tried? What was the result?

I have two accounts on this computer, the original 'Administrator' account and a second user account I created that has administrator privileges.

If I log into the default administrator account FF behaves exactly as I expect, if I change an option it saves the new value and honors the new value the next time FF starts up.

If I log into the user account I get the abnormal behavior.

My update problem was solved by permanently upgrading the second account to admin-privileges. So the two problems are clearly unrelated. Sorry if I got your hopes up, I know how frustrating this is.

Hopefully someone else might stumble upon the thread and go "a ha!"

Last hail-mary suggestion: Create a new account, install FF in that account, see if the behaviour repeats. If not, copy over the entire old profile to the new account, see if the behaviour suddenly appears. If it does, start working through the delete&reset options to clean out a corrupt profile without losing settings.

If the behaviour doesn't appear in the new account, and doesn't copy over, then the annoyingly unsatisfying work-around would be to copy everything important over to the new account, and delete the old one.

I uninstalled FF and reinstalled it.

If I log into the default Windows (administrator) account everything works fine. If I log into a user account (with administrative privileges) I get the incorrect behavior.

I installed/uninstalled FF several times, installing/uninstalling from both accounts. When I uninstalled I always selected the option where all my FF data is deleted so I wouldn't have any of the old profile hanging around. Still no changes.

I did notice one more behavior that might be useful to anyone trying to debug this issue.

After uninstalling FF and then reinstalling it the first time I ran FF after the new install I set the option for reloading my tabs. I exited FF and restarted FF and my tabs were displayed exactly as I would expect them to be displayed. If I then exited FF and restarted it again then no tabs were displayed.

The feature behaved correctly exactly once!

If you do not keep changes after a restart then see:

• http://kb.mozillazine.org/Preferences_not_saved

You can try to reset Firefox.

• https://support.mozilla.org/kb/reset-firefox-easily-fix-most-problems

If you reset Firefox then a new profile is created and some of your data (bookmarks, passwords, cookies, form data) is automatically imported and your current profile will be moved to the desktop (Old Firefox Data).

You can recover more data from the old profile (be cautious with doing that).

I've already seen the references to corrupted profiles and resetting FF was one of the first things I tried.

I noticed something the last time I uninstalled FF that gave me (false) hope that I was on to something.

When uninstalling, FF asks if you want to delete all FF data. I said yes but when I looked in the AppData user directory for Mozzilla there was still a profile for FF.

I manually deleted the profile and reinstalled FF. Brand new profile from scratch was created but nothing changed, The first time I started a FF session I set my options to save tabs, exited the FF session, restarted and my tabs were there. I then exited FF and started a new session and my tabs were not restored.

I would like to thank everyone for their help but I'm accepting defeat on this one, I've already spent way too much time on it.

FF is still my preferred browser and I will continue using it on my primary computer (Ubuntu) but not on this Windows laptop. It looks like I'll be giving Opera and Chrome a chance on this computer for a while.

Which security software (firewall, anti-virus) do you have?

Try to boot the computer in Windows Safe mode with network support (press F8 on the boot screen) as a test to see if that helps.