I have been stumped on this issue for a few days but with some digging I found what i think might be the problem. there is thread on DTV Tivo community that basically agrues that its the DTV box.
I'm wondering does anyone else out there use this a DTV hr10-250 sat box as a source and is experciencing the same problem? Hiss or pop while watching TV, changng channel, FF or RR on the tivo?

Also is there a source that can take a sat box and buffer the ever changing audio and video output a sat box puts out. I mean just watching an hd channel for any period of time you could get DD 5.1, DD 2.0, or just analog. Thats just audio. Video some movies are broadcasted at 480i some at 720p. There has to be a box that either buffers all these componets and streams them to your reciever flawlessly or do you have to wait till everybody get on the same page?

Just tsome thoughts,
mike

Your description of the behavior certainly sounds like it's the DTV box that's at fault, and unfortunately I'm not aware of any standalone buffer boxes - you really have to depend on the source to maintain a constant signal for the receiver and TV (which technically is the source's primary job, after all).