I have a MSI IM-GM45 motherboard (http://www.logicsupply.com/products/ms_9818) installed in a machine set up for HTPC usage. It is running Windows 7 x64, and has an older version of Vista drivers installed for its onboard GMA 4500MHD graphics adapter. These drivers are the only version that seem to enable HDMI audio.
The frustration I am experiencing is that when the TV and Receiver which are hooked up via HDMI is turned off.. the adapter then switches into an input mode where it enables extended desktop mode across an imaginary "mobile display" and the onboard VGA port where nothing is plugged in. And in random cases when the TV and receiver are turned back, the adapter does not switch back to single display mode via HDMI. This does not happen consistently which makes it even harder to explain.
When everything is on there are three displays, 1: Mobile PC Display, 2: Sony AV Receiver, 3: Display device on VGA. When the receiver is off, there are two displays, 1: Mobile PC Display, 2: Display device on VGA.
To rectify, I have to connect with VNC and set the display settings from there, very annoying when you just want to watch TV with a remote.
I've tried disabling the two unused displays from Device Manager with no luck. Short of just replacing this motherboard, do I have any other options?