STR-DN1050 Audio out (amp/TV & amp) setting doesn't work. no sound with HDMI out.

[Deders]

I'm using the reciever directly from my computer and it usually works fine, until I plug in a monitor to access the OSD.

My computer is connected directly to my monitor via displayport.  The reciever is connected to the same graphics card via HDMI.

I have 2 monitors I can use to output the OSD from the amp:
- My main monitor, (Dell U2913WM 2560x1080) I can switch the displays, fiddly but doable, digital connection.
- A Pacard Bell Viseo (1280x720) that only has a D-sub connector, so I use an HDMI to VGA adapter, this should not pass the audio through as the VGA cable has no signal path for audio.  Analogue connection.

Whenever I plug in an HDMI cable to either monitor, from either HDMI out A or B, the audio cuts out from my 5.1 speakers and my computer only see's the respective monitor as an output, not the reciever.

Canging the HDMI out setting from just Amp to TV & Amp and back makes absolutely no difference.

I have considered using Optical but I need to be able to have surround sound for games, as well as bitstream Dolby TrueHD etc, the best optical can give me is DTS.  It doesn't have the bandwidth for anything above this.