I have (had) this issue as well. Search around Missing Remote website and they have a tool that may help you. It helped me, but I do not have sound out of HDMI after 045 - 099 BiOS update.
Also, it seems there is an issue with BiOS newer than 045 having issues in general.
I also can't get sound out of HDMI after updating my DH61AG to the new-gen BIOS (099 or later). I have a 2nd-gen Core processor running Win7, and have tried clean installs, checking BIOS settings etc. with no luck.
I've seen this problem reported several places. Intel, will there be a fix?