We have a strange problem with our BT box: it seems to be turning the picture off on the tv. Every 15 minutes the picture goes off, but the sound stays on. I thought at first this was a problem with the tv as the problem occurred whether we were watching the BT Box or the DVD player. However, if the BT Box is turned off the DVD player and tv are fine. We've had the box 4 months and it has been fine so far. It just started today. Any suggestions of what the problem might be?