I got around this problem by 'remoteing' into my HTPC with the receiver off and changing the display resolution to 1080p. I used splashtop remote from an iPad (set to 'use desktop resolution'). I'm not sure if VNC or other similar stuff will work too, but I haven't tried it.
The audio problem I got around by disabling all audio devices apart from HDMI. So it doesn't get stuck on anything else!