I've recently bought a Hitachi smart tv and a Bush recorder (through which the tv is set up) but occasionally whilst watching the tv the recorder just goes into standby mode & therefore the tv goes off! .... Someone has told me that it's quite normal with modern tv's, but I'm finding it really annoying!
mine would go on standby at, I think, random times but flashes a warning on screen. pressing the exit button stops it shutting down. Unless you get a better answer you could try pushing the exit button from time to time.