A little update. I actually discovered that it is not a taskbar button that is appearing, it is an icon in the system tray. I never noticed because I always had my taskbar pretty full so it looked like a new button pushing all the others over, but I saw it one time when I only had a couple windows open. I just happened to be looking down there and saw an icon turn on and off rapidly a few times in the the system tray. It expands the tray which makes the other buttons smaller.