So I have an odd issue.
Hardware that matters listed: ATI 4670 & Samsung HD 1080 HDCP compliant TV running on Windows 7. Currently hooked up with DVI to HDMI (it doesnt matter as I can watch movies from DVI to HDMI, but I also tested an HDMI to HDMI cable)
My home theater PC was working fine for 3+ years with an Nvidia 8600GT. One day my hard drive crashed, so I rebuilt my system with a new drive and upgraded the video card slightly to an ATI 4670 with Windows 7 again. After windows installed, I installed WinDVD 11 and I can immediately watch Blu-Rays on the TV.
Directly after installing new ATI drivers, I get a nasty error message from WinDVD that the movie is not supported in the viewing environment or something along those lines. I haven't bothered to hit the Corel forums because..well..why? It worked perfectly until I installed the ATI drivers. I uninstall the ATI drivers and I still can't watch movies now. The ATI install fudged up the HDCP key somewhere and I can't find a solution. Of course I've tried to reinstall WinDVD, and that did not fix it. I also downloaded the trial of Arcsoft's Total Media Player, and same thing. I get an error about my hardware not being supported...but it is. In both players, the movie starts for about 5s then the player belches out the error message.
I mean, literally, my steps were Win7 install, install WinDVD, watch Blu-Ray (using Microsoft's generic drivers), install ATI drivers, can't movie play Blu-Ray. I'm using the 8600GT in another system. Could I simply put the 8600GT back in my Theatre PC? Sure, but come on. Shouldn't something as silly as this just work? I'm at the point of just buying another NVIDIA card or reinstalling Windows 7 and keeping MS's basic video drivers which worked.
Does anyone have any idea what the ATI is doing to the HDCP key (which I think is the problem) and how I can fix it? And why would it leave it broken even after uninstalling the ATI drivers? I did some searching here, and the general consensus seems to be HDMI with ATI is a bit of a hit and miss.