Sound is quite intermitent on my Cable HD channels. Also there's a small pixilated horrizontal line that comes and goes. It does it on all HD channels. No problems watching regular channels. The cable box is a Scientific Atlanta Explorer 3250HD and my receiver is a Yamaha RX-V800. The cable box is one shelf above the receiver. I've heard that a too close receiver can cause interference with the box. Thought I'd ask, before I unplug all the cables. Any advice much appreciated.