I had an issue with one of our LCD tv's not getting signal through HDMI with the C31/700 box in that room. We ended up going with the 10-pin Component cord for that tv. No issues after that. Some TV's do not play nice, when it comes to HDCP with certain hardware.
I used to have the same issue as you are, with the UVerse DVR I had. I had to use component connection. Funny thing is that after we put in a Home Theater in our Living Room. Using a Denon AVR-1612 as HDMI switcher. The problem with the HDCP handshake went away.