Not a smart tv problem specifically, but the inability to adjust volume level while on mute (at least adjust down). I often turn the tv on after the rest of the household has gone to bed and it's way too loud, so I hit mute. But as soon as I hit volume down, sounds comes back on at the initial loud volume! Aargh. Only thing is to navigate away to a silent input, adjust volume, then navigate back to previous channel. Annoying. I have seen this feature once before (Sony I think).