I bought a QE75Q80B 4 weeks ago and experienced the same problem. When the tv's turned off and you switch on again later, the only way to re-establish the Sky broadcast is to switch the Sky box off and on and go through the reboot process on the Sky box. I've tried every fathomable solution but none of them have solved the issue. These include a visit from a Sky engineer, changing the Sky box, remote access by the Samsung tech team who said they tweaked various things, factory resets on tv and Sky box, new HDMI cables and power leads, changing the HDMI port etc etc etc .....!!! My previous Samsung, also a 75", worked perfectly with Sky although the screen went after 18 months - and I only had a 1 year guarantee. No one at Samsung has been able to give me any assurances about this issue. So I'm awaiting delivery from Amazon of a very large box in order to return the tv and I've already decided I've no alternative than to buy an LG or a Sony. Heading down to Richer Sounds today to check these out. Seems to be very widespread with newer Samsung TV's.