I have a Panasonic TC-L32U3 HDTV. It's always been detected as a Panasonic TV by the GTS 250 I was using (which is based on the 8800), the 660 Ti I tried recently, and the 7970 I now have. It was also detected as HDCP capable in the "View HDCP status" tab and CyberLink's free BD & 3D Advisor tool by my GTS 250. You should check for HDCP status too. HDCP status is read by other devices via reading a digital signal sent out from an Intel chip in the device. All digital ports should pass the signal, but it would appear that is not working well in some cases.
The 660 Ti showed my TV as not HDCP capable for some reason. I also started having problems with BSOD when switching from TV to PC input using the 660 Ti, and I couldn't even boot to desktop when using a DVI to HDMI adapter with an HDMI cable. On my friend's 5 yr old Dynex TV though, it booted up fine and had no BSOD with input switching on his one piece DVI to HDMI cable. His TV was also detected as HDCP capable with the 660 Ti.
This left me, Newegg and MSI (brand of 660 Ti) speculating a possible incompatibility between the GPU and my TV, or a defective GPU. It also uses a special BIOS that allows over volting, and techs have told me that in itself could cause such problems. I refunded the 660 Ti and got the Sapphire Dual X 7970. The 7970 has no problem switching inputs on HDMI, but it would not even boot up with a DVI to HDMI adapter and HDMI cable.
I should mention that my TV is one that has a VGA input intended for PC use, but the manual states PC use is NOT assumed. When they say things like that, they probably mean it's not intended to be connected digitally to a PC. In my case, it only means I can't use DVI and I can only use HDMI audio as stereo via my TV speakers, so I use an optical audio cable to my receiver instead.
The reason I tried DVI via an adapter was because my TV is on a table behind my desk and the only cable I have that reaches is my 8' HDMI cable. It's also because I wanted to try the ATI audio enabling DVI to HDMI adpater I bought in case multi channel HDMI audio didn't work.
In summary, from my findings it looks like such things are caused by the port design of the TV, and what connections are allowed for full PC functionality. On yours, you may only be able to get it to work via DVI to VGA, but I would also try a one piece DVI to HDMI cable instead of using an adapter. It's a shot in the dark, but such cables can be had cheap and it's worth a try.
Also, try connecting via each HDMI input on the TV to eliminate the possibility of one working but not the others. Good luck, I plan to stay tuned to this thread to see if you come up with a solution. It's not a very common problem, so those of us having it like to get input from others.