I have just connected a Cabelvision HD box to my X45, I no longer am able to receive STD tv broadcast for NBC, CBS, FOX and can not receive the HDTV broadcast for these networks. The ABC HD broadcast works fine. I am also able to pick up HBO and other HD broadcast but unable to pick up others auch as ESPN. The tv will tune to the station display the program info and then go blank. Does anybody have any ideas as to how the problem can be fixed?