Have you tried a forced software reset? If not try it first, solves a multitude of problems.
1) Press and hold down back-up button on box.
2) Disconnect & reconnect mains power while holding back-up.
3) After reconnecting power keep button held until all 4 lights illuminate and update message is displayed on-screen (approx 30secs).
4) After download completes (approx 10 mins), leave in standby for 1 minute then switch on & allow channels to refresh.
Otherwise, suspect faulty Low Noise Block on dish.
Cobweb
October 2005