Re: No audio from HDMI (MCP89 / Geforce 320M): Reason: no connected devices detected
It looks like you're using driver 195.36.31. There have been a number of changes related to audio-over-HDMI since then. Can you please try driver 256.35 and see if it makes any difference?
In the meantime, I'm working on tracking down HW to try to reproduce this.