Long story short, I have had this problem with my last three dell laptops over several years now.
Dell studio 1737
Dell studio 1747
dell inspiron 17 SE
Hdmi output works absolutely fine for a few weeks after format/reinstall then the audio just stops. Settings are fine, video is fine and there are zero changes... It just randomly stops outputting audio over hdmi. It comes out the laptop and doesn't detect the tv/receiver as an audio device.
This has occurred on 2 different receivers and 2 different TV each and every time the TV detects the laptop, laptop detects the tv/receiver but no audio!
"Agent" posted this was a known issue with the Intel board (?) but I can't find the thread again. I was hoping there might have been a fix out out for it...