I continued with Firefox 40 to avoid the problems between the later versions of FF and NTB/IS.
Today, Nov 4th, the new Norton Toolbar/Identity Safe extension v2015.5.6.76 downloaded itself in FF40 and I decided to click on Install button despite the FF warning message.
Fool that I am I believed as it is Norton it is not going to do damage is it?
It promptly overrode my home page setting and treated me to Norton Safe Search. I reset my home page to normal and opened a new blank tab. Up came Norton Safe Search again.
I checked the settings, switched off Safe Search, closed FF and restarted. Norton Safe Search had taken over and still came to life whenever a new tab was opened!
I went into Add-ons Manager and disabled the new extension. The toolbar disappeared, but still everything I try results in Safe Search taking over. It also seems to have disabled the normal right button click context menu ability in FF.
I went back into Add-ons Manager to uninstall the add-on, but can't do anything. It is behaving like MALWARE!
How do I kill it?