My ROKU 3 has started to give intermittent sound during programs. I will select a station Netflix, YouTube, Amazon... pick a show and the sound goes in and out. In the top right hand corner of the screen there is a headphone icon with numbers around it. When I plug in headphones to the remote I can hear when I remove the headphones sound becomes intermittent again. I reset the unit once but it has come back, any idea what the problem might be and how to fix it?