First try loading the latest video drivers here: Intel® Download Center select the operating system and download the latest one.
Also, I would like to know if you are getting sound connecting the HDMI directly to your computer.
I have loaded the latest drivers and also tested some older drivers. No luck.
I have connected the PC to the AVR and also the TV directly, but both do not play any sound. Both are recognised correctly and are showing in the playback devices list when connected. In both cases video shows correctly.