I have a ATI Raedeon 3000 that used to output to the 42" and I could stream to the tv. When I connected the hdmi cable the vga output to the monitor blanked and I only had the background on the monitor. The full desktop with background was displayed on the TV. Then the VGA cable broke and when I replaced it I no longer had video or audio to the TV via HDMI.. The monitor still switches like before and the TV and computer will recognize the TV as monitor 2. I checked the HDMI cable by hooking it to the Bluray and it works fine. I am at a loss and miss the streaming.
So your HDMI connection to your TV is no longer working, but you have a different VGA connection to another monitor which is still ok?
My first suggestions would be to check that the TV connection is actually enabled, by checking that the desktop is actually extended to your 2nd monitor. If the TV is monitor 2 then right click on the Catalyst Control Centre icon and click extend desktop on the 2nd monitor or use windows display options.
If's that's all enabled and you still aren't getting a picture through the TV then check that the resolution is something the TV can handle properly.
I don't really understand how a broken cable to the other monitor would stop the HDMI cable from working properly, unless there is something I'm missing.