Does this happen with all AV sources available to your set, ie TV, SAT/STB and/or DVD (if you have any connected, that is) etc.? - If not my guess would be that it might be scart not connected properly - or something else wrong with the cabling perhaps. This can happen especially if one uses the motorized stand (they tend to 'loosen' in their sockets). That said, this issue would though hardly be helped by turning the set on and off... Always best to start checking the least complicated things such as cables. Otherwise no idea, sorry.