Media center audio issues

Ok so hoping someone can help me out here, first off heres my specs :

ASUS M3A78-EMH HDMI 780G motherboard
2gb Kingston Value ram
80gb SATA hard drive
8800GT (Folding & lan box)

So I have the Video connected to my TV VIA HDMI from the 8800 using the DVI - HDMI adapter that came with the motherboard, and for the audio I have a 3.5mm cable - phono going into the 2 phono ports on the back of the TV which link with the second HDMI port.
Now first time I set this up it all worked fine but now I dont get sound, now since then I have had the 360 plugged into that HDMI port (HDMI port 1 only seems to do 1280 x 720 not 1366 x 768) so wondering if that has anything to do with it?

Well try unplugging the 360 and see if that fixes it?

360 isn't plugged in?, its only one HDMI socket, I unplug one when I want to use the other.

So from your PC its DVI then to your TV its DVI-HDMI...my guess its probably something to do with your TV, have a quick look at the audio settings on it just to make sure the HDMI input is still enabled? Ive also heard stories about Nvidia having driver issues with outputting HDMI...

No, the graphics card has a DVI - HDMI adapter and from there its a HDMI cable to the TV, for the audio its a 3.5mm - phono cable going from the sound card to the input on the TV.

Hmm, I think maybe your TV is getting confused about which audio signal to accept..it might be that the HDMI is carrying a blank audio signal but your TV is cancelling the phono audio signal in favour of the HDMI input. Try changing the DVI slot on the 8800? What TV you using mate?