For ages I've had my tabs automatically restored when opening Firefox. But as of the last few days it won't. The old links are saved so I can restore them one by one through history but that's not automatic. And if I click on restoration in History it will bring up a whole bunch of old tabs not neccessarily from the last session.

I'm on the same computer as I've been for over a year, so I don't know what what the problem is. I've searched on it and tried to re-check the box for this function. But it won't apply...