I've been using Tab Groups add-on for as long as it was discontinued as a standard feature in Firefox. . Since I installed Grammerly a few days ago, sometimes when I open Firefox Tab Groups malfunctions. It starts cycling through all the Tab Groups one at a time. The only fix, is to use task manager to close Firefox and then copy a previous.js into the Firefox folder and change it’s name to sessionstore.js I can then open Firefox. Unfortunately I lose some of the latest history when I have to do this. I’m using Firefox 50.0 Any suggestions,