This problem first occured when my friend came over and we were going to watch a movie on my HDD on my HDTV. I recently upgraded my video drivers. For the first time, when I went to the Nvidia control panel and selected DualView, then I tried all of the other settings (stretch, clone, etc). nothing happened, no picture on TV.
After uninstalling all my video drivers and using driver sweeper to remove any traces of them in the registry or temp files, I reinstalled old video video drivers I know for sure have had dual view working before, but I still can't get any picture on the TV, monitor is fine.
I thought the port may have gone bad so I tried both the TV and the Monitor in each slot and they all worked, but when I plugged in two at the same time, neither had any picture till I unplugged one of them. I restarted the computer knowing this may be the problem, but even after a fresh boot with both the TV and my monitor plugged into my card, I could not get a picture on the TV, but I do have a picture on my monitor.
Can you set the resolution for the TV to 1920x1080? Other than that if the control panel can't detect both at the same time I don't see why it shouldn't try to output two signals at the same time. It's what Nvidia cards have been capable of since I think like the Geforce 4 series.