So I downloaded the English Demo and had the same problem that this thread was started for... the infinite loading screen after the ladybug movie. That doesn't bode well for this game. I was really looking forward to playing it too. I've got an Athlon 64 3800+ processor as well.
I'm downloading the german demo now to see if it works.
e: The german version doesn't work either, infinite loading screen at the same spot.