Firefox won't restore sessions/tabs

I don't know what I did, but every time I start it, it opens with just a single, blank tab. No homepage, none of other tabs. However, I can get them back.,..by manually typing about:sessionrestore EVERY time. I even tried going to about:userconfig, but I still get a single blank tab when I first start.

(Anyone bet it will fix itself by the time someone replies, just to make me look bad?)

In Firefox, under TOOLS > GENERAL tab, what does it show for
"When Firefox starts:"

You probably want it set to 'Show my home page'.

Also, do you have something listed just under that in the Home Page field?

If either of these are set to Blank page, Firefox will simply open without displaying a web page.

It is set to "show my windows & tabs from last time."

Found this"

It is about this setting:
Tools > Options > Privacy : History: [X] Clear history when Firefox closes > Settings
If the Browser History is cleared then restoring tabs doesn't work.

The box wasn't checked.