Not surprised... HDCP doesn't get redetected correctly with 7.10 firmware.(there is a whole thread about this happening with Zenith C32V37)
Here's the trick:
Make sure only DVI cable(no component connection) is connected from box to TV
Turn TV on and switch input to DVI.
Unplug cable box long enough for it to reset.
Plug cable box back in and let it "hunt" and "dl"
When it comes back up, your DVI should work.
One problem. If you switch your TV to any other input, or turn the TV off while the cable box is "on" you will get the error again. If you want to use other inputs or change channels on the TV, make sure you turn your cable box off first! Always turn TV on switched to DVI before powering up the cable box, or you have to go through the 5-10 minute reset again.