I would hesitate to call this a stupid question, but....
DirecTV uses all transponders. There are roughly a dozen (16?) channels on each transponder. When you change channels the receiver selects the appropriate transponder.
Since are suffering pixelization on the DirecTiVo but not on the regular receiver, it would be a good idea to look a little closer to home than the satellite. The DirecTiVo tuner may be less sensitive that the standard receiver, or it may be a cabling problem, cable length, or multiswitch issue. The quick test is to swap the DirecTiVo and standard receiver temporarily and see if the signal levels change.
There's a difference between needing help, and just being plain ole' lazy.
"You cannot teach a man anything. You can only help him find it for himself." Galileo Galilei (1564-1642)
HR20-700 with 2 TB, HR22-100, HR22-100, HR22-100, HR23-100 all running 0x5cd and networked.