If you use Delete browsing, search and download history on Firefox in Firefox 3.5 and later to clear the 'Browsing History' when you close Firefox then restoring tabs from the last session ("Save & Quit" or "Show my windows and tabs from last time") doesn't work.

You can check the startup setting Firefox > Preferences > General > Startup: "When Firefox Starts": "Show my windows and tabs from last time"

Yeah, this works some of the time. But don't count on it. I'm running Windows XP 5.1 SP 3 and FF 3.6.9. Most of the time FF comes up with the tabs from the last session, but on 1 of 5 or so start-ups it shows just the AOL/Netscape home page. All of the history is clear. The screwy thing is that sometimes it will bring up the old tabs the next day. Roulette type of consistency, kind of like the rest of Windows!!

I've never had a problem with restoring tabs after a crash or forcing a close with the "Show my windows and tabs from last time" .

Relying on Save and Quit by choosing the other possibilities ("Show my home page","Show a blank page") is however quite uncertain and can fail at any time (closing after an update is a good example that can go wrong).

If you consider session data important then make a backup of sessionstore.js in the Firefox Profile Folder or bookmark all open tabs.

Okay this is how i got Firefox to remember my tabs. First go to the "Tools" button in the menu. Click on Options. In the general section there is a place that says "When Firefox starts" next to it there is a scroll menu. The bottom option should be "show my windows and tabs from last time" select that option and click "OK". I hope this helps ^^