I have a Panasonic TC-L32U3 TV. It's always showed as HDCP capable in NCP with my GTS 250. Recently I bought a MSI 660 Ti PE OC and started having problems with the TV being shown as not HDCP capable, the Nvidia HD Audio device in the W7 Sound panel showing as unplugged, and BSOD when switching from TV to PC inputs using the HDMI port. On either DVI port it wouldn't even boot to desktop. On my friend's 5yr old Dynex TV, everything worked fine using DVI.
One thing I didn't try is using the main HDMI input on the TV, in the off chance the other HDMI ports on the TV are not HDCP capable. I didn't because NCP shows the TV as HDCP capable when using the secondary HDMI ports when the GTS 250 is installed. It was also because I felt having to use an HDMI switching box, if that were the problem, would be unacceptable. I also ran a test using Cyberlink's BD & 3D Advisor, which checks for HDCP capability in the GPU an display. My TV passed that test while using a secondary HDMI port on the TV.
I am thinking this very well might be a display compat problem in the latest drivers affecting some if not all 600 series cards. I tried both 306.23 and 306.97. A tech in local PC store said they've had lots of returns on 600 series cards for driver and compat problems, including some display compat issues. This has me wanting to try a 7950, but drivers aren't exactly AMD's strong suit either. I may just wait and see if Nvidia's driver team acknowledges any display comat issues and fixes them.
Meanwhile, I've found a 3 input to 1 output HDMI switcher by Masscool on Newegg that has auto, manual and remote control port switching. It supports HDCP passthrough, though no mention whether it supports ARC. It's only $20 and is getting great reviews. It's not an ideal solution, and I don't even know if it would solve the problem, but it's a whole lot better than buying a new TV after having my Panny for only 1 yr, which has a prety decent picture. http://www.newegg.com/Product/Product.aspx?Item=N82E168...