How have you set Firefox to do that? Have you set Options > General > "Show my windows and tabs from last time"? Have you also set up Options > Privacy so that the history is not cleared?

Did you do it the other way? Did you close Firefox from the menu or with the keyboard shortcut, and choose "Save and Quit" from the popup box?

The latter is the way I get Firefox to restore my previous session, and it works every time. One has to avoid clearing the history in order for the session to be kept.

First, thanks for a really prompt response! Here's what I've done --

In my options, I've always used "Show my windows and tabs from last time." I've also set up privacy for "Remember History." No matter WHICH way I close FF, I never get the pop-up menu. If I simply tap out the "X" from the browser window, or if I chose "Exit" from file, nothing. It simply closes.

I even tried out the beta FF16, but had the same exact results. And in my pull-down history menu, I only EVER have "today" and never a previous day(s) or longer period selection. I've used FF for years on my other computers (including four others in my house at the moment) with no problem. I've made sure all my settings are switched to preserve history: NO auto deletion of history upon exiting - nothing like that. And Google Chrome, Opera and IE browsers all work perfectly on this computer. I just don't get it. And - as noted: am very frustrated by it. But again: many thanks for your response.

If you use cleanup software like CCleaner then check the settings for the Firefox application.

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

Some security software does have virtualization or sand-box features that can cause problems by protecting and restoring files in the Firefox profile folder.