For the past couple of days whenever the Airtel HD STB is switched on either I do not get the picture immediately (even though I get the green signal light in the STB) or if I get the picture the sound does not come through. However surprisingly I receive sound in the `Airtel Home' channel but complete sound outage in other channels. I had to switch off the STB and switch it on back and wait for atleast 5 minutes to get back the picture and then sound. Any idea what might be the problem?