I just had a similar issue earlier yet no one responded. What is your build? Specs? PSU is important as well. Did you install the drivers from the disk use windows to find the drivers or download them from the internet yourself. Also make sure you install drivers for the HDTV to your PC specially a newbuild.
I have this issue before on my HDTV, but one time I tried, and it works because I change the refresh rate to 60Hz. I think it really said 'not supported'. The cause of this is because the refresh rate is not supported by the TV, good luck .
Radeon HD 6770
2nd gen Core i5
Win7 x64 personal
Trying to connect to my 19'' Polaroid LCD via HDMI - TLA-01911c (Four years old)
So, after all my digging I am convinced that this is a Windows 7 EDID issue.
I fully-uninstalled the Radeon GPU and tried the onboard GPU and experienced the same issues.
I have tried all types of resolution settings that should be compatablie with this monitor.
Very frustrating because I can actually view Safe Mode on the Polaroid LCD, and even set&view the resolution to 720p in Safe Mode only.
I'm gonna try AMD customer support and see what they say.
Fixed!! I think the key was un-installing BOTH the Radeon and OnBoard GPU adapters. This allowed the tv to work via the standard VGA adapter. Then I re-installed the Radeon GPU and now the LCD works in 720p. Manual says the max is 1440x900, but I cant seem to get it better than 720 at the moment