Loosing Sound (and Audio Device) on Resuming Power On

Hey Guys...I hope there is an easy fix for this. It has been a long road getting everything working and this seems to be the last piece that is giving me intermittent problems.

I have a llano A8 AMD based system running on an ASUS F1A75V_EVO motherboard.

This is connected via a single HDMI cable to an Onkyo TX-NR809 receiver which, in turn, is connected into a Vizio TV also via a single HDMI cable.

I am running WMC on Windows 7 64-bit.

What happens is that on power on of all devices (and PC coming out of sleep mode) I will occasionally not get any sound. Usually restarts of various devices will resolve the issue, but today I figured out exactly what is happening.

In my Windows Playback devices I have 4 devices listed:

1. AMD HDMI Output - AMD High Definition Audio Device - Default Device
   Driver - AMD High Definition Audo Device - 10/18/2011 - 7.12.0.7704
2. Speakers - Realtek High Definition Audio - Not plugged in
   Driver - Realtek High Definition Audo - 11/23/2010 - 6.0.1.6251
3. Realtek Digital Output - Realtek High Definition Audio - Default Communications Device
   Driver - Realtek High Definition Audo - 11/23/2010 - 6.0.1.6251
4. Realtek HDMI Output - Realtek High Definition Audio - Ready
   Driver - Realtek High Definition Audo - 11/23/2010 - 6.0.1.6251

When my sound is working properly it is listed as coming out of the AMD HDMI output - which would make sense to me since the HDMI is built into the motherboard and controlled via the AMD controller.

However, when my sound is missing, I looked at the Playback devices and the AMD shows as grayed out and listed as disconnected. The green volume bar is moving on the Realtek as if the sound is coming out of there, but of course I don't have any SPDIF connection, only the HDMI - so I am getting no sound out of the speakers.

The last time it happened I switched my receiver on and off a couple times and restarted WMC and the AMD showed as available again and I was able to get sound.

Can anyone explain why this is happening and hopefully provide a fix for me? Is there a way to prevent the HDMI from going offline in the first place?

Another piece of info which may be relevant is that I have my Onkyo set to passthrough the PC input when the receiver is off. So, when my receiver is turned off I can still get PC output on the TV (in case I want to have slideshows or simply don't need sound). I am wondering if this might cause it - however the issue doesn't happen every time.

thanks!

I have used the EDID override procedures mentioned elsewhere in the forums.

I thought the point of the override to make the the PC hang on to this info even when disconnected?

I set up HDMIYo to assist with some display issues...I would think that a re-init of HDMI would reset the audio too :/