Originally Posted by beowulf7
Yes, I also noticed this. Open up Firefox and you'll see a number in the top right that refers to the tabs that are open. Click on it to see all of the tabs and close them out. Then when you exit FF and relaunch it, it'll have just the "Top sites" screen.
I only use 1 tab and this happens from time to time. It's odd because the audio will just start playing from a video when the screen is off and locked. No video, just a dark screen playing audio.