I believe that happens when something goes screwy with ozcompat.
Eon config (fresh install) fired up without compat libs on 3.5.1.
Motocross demo is kinda loading, but it looks like there is a problem with libSDL as it is all grey boxes and black screens.
Best of luck getting any help from Eon Games. I thought they closed doors a while ago.
You can still buy games, as it is all automated, but I dont know what kind of support they still offer.
Too bad too. I was looking forward to more ported Xen Games.