My daughter's TV and Dish receiver also gets occasionally crossed up on Digital Rights Management for "true HD" content, which uses only HDMI or DVI connectors at the TV.
If it doesn't fix itself with a power-off, it does when we re-boot the TV (which is a fairly complex computer) by unplugging it briefly. Problem is not always a cable, there is a communications protocol required between source (BluRay player, HD cable receiver or HD satellite receiver) and the HD display (TV or monitor) that says: "the manufacturer of this display paid the license fees" and sometimes the messages get out of sequence, or the answers get forgotten in the tables maintained by the source box. This will happen particularly if you start switching different displays at a single output of the HD video source.