For the past few days I've noticed that 3 channels are blank. the Golf channel, NBCSN and CNBC. Tried rebooting box and picture does come on, but after a few seconds picture goes completely blank (black screen). Yes, I've checked all connections, but I don't think that was the problem because if it was a connection issue I would have problems with all the channels and not just 3. I called customer service and they said they'll "look into it". Anyone else having problems with these 3 channels?