Radeon HD 6950 will not detect HDMI

Until recently I had my computer connected to a stereo amplifier via HDMI cable, from which I had a TV connected also via HDMI cable, through the stereo. So the stereo had the computer plugged in to it, and also the TV plugged in to it.
Then it all stopped working.

Now, with the setup described I get no picture on the TV on sound through the stereo speakers.

However, this is where things become strange...

I can connect my TV directly to my computer w/ an HDMI cable. I get sound and video through the TV just fine. (This is without the stereo connected)

When I connect my computer to my stereo, without the TV, I don't get sound through the stereo. The sound manger doesn't recognise that there is an HDMI cable plugged in, connecting computer to stereo. I've enabled/disabled various playback devices and also made sure all devices were visible in the audio/sound manager. (right clicking on the speaker icon on the tool bar)

To check whether this was a computer or stereo issue I connected another computer to the stereo with an HDMI cable, and I got sound. This makes me think it isn't due to the stereo but on the PC's side.

I have completely uninstalled and reinstalled the GPU drivers, updated Realtek audio drivers ect. Nothing has worked.

Oddly when I uninstalled the GPU drivers and had the computer connected to the stereo, and the TV connected through the stereo I did get picture on the TV, but no audio. Reapplying the GPU driver updates once again gave me no picture on the TV.

Also, when restarting the computer, with the stereo and TV connected in original way I do breifly get picture on the TV during the BIOs boot stage. Then back to nothing.


I'm running-
GPU- Radeon HD 6950
CPU- AMD Phenoom II X4 965 3.40 GHz
MoBo- ASUS M5A97
OS- Windows 7

Stereo- ONKYO home theater
TV- Panasonic I don't remember.