Heat related or some connection. Your usual technician when they service it (maintenance is mandatory on this type design) will clean the dust out, check the fans and may unplug/plug in connections as they do the usual yearly work.
How long since the tech saw this one?
My HDTV has been doing this for around 6 months. I have a new monitor so I don't need it but would like to have it work better. The tv does not turn on unless I physically hit it or shake the box. Once on, it works for variable amounts of time, but inevitably turns off again. In the "off" state, the indicator light blinks on twice for 1 second each, then is blank for 2 seconds. The screen flickers slightly at the start of each flashing light cycle. The tv can start working immediately if I hit/shake it again, but it sometimes takes quite a while to turn back on (it will never turn on if left alone).
I called samsung and they told me to bring it to a repair shop, but that'll likely cost me $50 right off the bat (+actually getting it fixed). I read about similar problems suggesting to change the lamp/PSU/capacitors, but I thought I would ask about this specific model.