This may be a repeat of what somebody has already mentioned, but maybe part of the problem is that Comcast's version of the DCT 6412 does not fully support firewire. My TV (Mitsubishi WD-52825) has a built-in DVR (they call it a PVR) as well as 2 firewire inputs. Because the firewire is not fully supported by the Comcast box, I can see the picture just fine but when I press "Guide" or "On Demand" or "Info", I see nothing unlike when I am using the component or DVI outputs (then Guide, Info or on Demand work). So if I want to record to the TV's DVR using firewire output (like I am doing as I type with "Stars On Demand's" "Harold and Kumar") I set up the viewing using DVI output then I switch to firewire to record. The reason for doing this, is that the firewire input is the only truly digital input that the Mitsubishi's DVR will record from. I can also record directly to DVD recorder but my DVD burner has not digital inputs like component, DVI or firewire (only has digital outputs).
Wayne