I usually connect my htpc (Point of View ION-motherbord) to my tv through hdmi and have no trouble with this, but as I also have an (older) projector which only handles vga I tried connecting it yesterday but couldn't get XBMC to run at resolutions higher than 800x600. I know for a fact that the projector can handle 1280x720 without a problem, but how do I tell this to XBMC (or Xorg)? I have tried setting the mode in xorg.conf but failed miserably
Have you tried booting from a Linux boot disk on the same computer? It mat be that the hardware cannot handle that aspect. I know xbmc and my tv can handle high resoloution widescreen but I end up having a square picture on screenshots because the hardware does not do widescreen. Maybe your hardware down not match up to certain projector resoloutions
Thanks outleradam for the suggestion! I spent most of my evening yesterday trying to figure out working ModeLines for my projector and managed to get it running at 1280x720 in the end. The trick was that my xorg.conf specified NOT to use EDID modes, but the supported VESA/X Server-modes were 800x600 max. When I re-enabled EDID modes, 1280x720 became available again.