Installed Firefox 47 today on windows 10. Browsing reddit with the "reddit enhancement suite plugin" active (I dont think this is the cause, but listing it in case). Several times today, I've clicked a link (once to forbes.com, once to usatoday.com, and once simply to visit the reddit comments for a post- then subsequently clicked the "back" button, and had nothing happen. In each case, when I long-clicked the back button to view the history, I saw the latest page I'd clicked to repeated 6-8 times in the history. This didn't happen with prior versions of firefox (also with RES), or with chrome.