I have set Firefox so that every time I start it, it shows the tabs from last time. However, just recently it has started with the tabs from last time plus an extra tab. The other day I installed three addons which all required Firefox to be re-started and each time it did so, there was an extra tab so that by the end of my addon session I had three extra unasked-for tabs. Not a problem really, just an irritation that I want to stop. How can I stop this? Until recently this did not happen and I just got the tabs from my last session unless I had closed them before shutting down Firefox. Even if I make sure that there are no new, unused tabs before shutting Firefox, I still get a new tab when I start it again.