Thanks for the replies. I guess what I am experiencing is macroblocking? Am I to understand that there really isn't a fix for this, short of changing providers? Fios is not an option. Sorry for the semi-hijack, but I've looked at the DVDO website for info before, but really had no idea whether the products could help.
This problem has rendered some of my favorite channels nearly unwatchable, including Space, Speed and Military.