I've recently bought a samsung 961bf monitor and it's been good. However, on two ocassions my screen went blank and there's this "analog/digital" box popping up as if it didnt have any signal. It happened twice when i was watching movies on windows media player.Everything on windows was still running fine as i can hear the movie playing without the display. I pressed the "source" button on the monitor for a few times to detect the signal but it wouldn't work. So i had to shut down my pc and turn it on back.And then the display comes back. Can anyone tell me what's wrong with my monitor?