What "cable hd channels?"
Is this any/all HD or SD subchannels, or just one particular local offender? I'm guessing the local channel PSIP data is tickling a bug in the 612 firmware. (This doesn't happen to us, and we've got two 612s and about 30 channels+subchannels.) Either the station will eventually get it's act together or else Dish will patch the bug.
Since last Friday, you have been in need of a rescan on those local channels, too. Did you do that? Best to delete them all first, hit the Done button to clear out the 612 memory, and then go back in and hit the Scan button.