(In reply to comment #11)
> It's a problem using any connector, VGA being another one I've tried. I did
> the installation by these instructions to the point, so I shouldn't have
> fglrx installed (http://forum.xbmc.org/showthread.php?tid=174854).
> I can try without acceleration if that's fruitful for debugging, but that's
> not a useful end result for me.

Yes, it's useful for debugging.