I am having this same issue.
Just switched over from a dedicated gpu so that I would be consuming less power only to find out intel 4600HD graphics has a severe HDCP bug.
My system: gigabyte z87-ds3h with 8gb ram, i7-4770k cpu, win7 x64 professional, ceton infinitv6 for cable card tuning and hauppaugge 2250 for ota tuning. The HTPC is connected to my onkyo TX-SR805 via hdmi and then hdmi to my Samsung lcd tv. The issue Is with windows media center playback of copy protected material. I have no issue with blu-ray playback just protected cable channel playback.