Did you get the correct cable company set up during Guided Setup? If you go into Setup and look at the channel list do you see the non-HD channels listed? If so, are they unchecked? If you get HD channels that are not ClearQAM then the cablecard seems to be working. Can you manually enter something like 26-1 (typical digital, non-HD channel).
"I'm just one story in a two story town." Bon Jovi