I have an Asus G51VX laptop with Win7 Home Premium 64. It has an Nvidia GTX 260M video. I have tried, unsuccesfully, to connect it to my LG 42" Plasma using the HDMI 'out' on the Asus to the HDMI 'in' on the LG. I have gotten these different messages messages depending on configuration setting: "no signal", "almost HTPC compatible, or "invalid format". Of course, LG blames Asus, and Asus blames Nvidia, and on and on...
I have tried various Nvidia drivers, and various Realtec drivers to no avail. I could hook the Asus using VGA out, but the pix isn't too good. One final note. My son hooked up his Sager laptop to my LG TV, using my HDMI cable and my LG TV found it immediatley. I have also tried the different Function Keys provided by Asus for my laptop.
One final note: I was told the Nvidia driver I upgraded from Vista to Win7 did not support clone mode. I tried new drivers from nvidia that supposedly fix this problem. This didn't work either. Sure could use some help.
I have tried different drivers...didn't solve the problem. So far, I have tried older Nvidia drivers supplied by Asus, different drivers from Nvidia site, and different drivers from Realtec. Keep in mind that the original audio drivers were from Realtec even though Nvidia provides audio drivers for the GTX 260M. One final thought...I am not able to configure SRS or even access SRS.
It sounds like a driver issue to me. You could try downgrading to an older NVIDIA driver to see if that does the trick, as older versions tend to be more stable. Otherwise than that, I don't have much of an idea.