I have had this problem for a while now, done full power scan, updated firmwear, changed all cables etc and nothing seemed to work.
I have now found that the connection where you plug the satalite cable is damaged inside. You can pull it apart and it should seperate into 3 parts. One of the part has two prongs which the spike from the satalite cable should sit between, my spike is now floating inbetween therefore not connected correctly.
This is the only thing now which I think could be causing the problem. My box is constantly cubing then saying bad signal in a blue box. I have pushed the prongs together so the spike connects properly which makes the box work correctly but you only get an hours worth of watching before having to repeat all over again!
I am now attempting to find a replacement to see if that will fix the problem-if not I'm affraid I will be giving up.
Hope this is helpful
Andy, August 2010