I had this problem on an old machine running 2.41 - no swf files show up at all when loaded into a deck.
In Avenue, the demo files show their properties in the clip property editor, but their place in the deck is a blank black square.
Elsewhere in the forum someone suggests that this is because the Flash Player needs the Active X component installed separately. I've done this but still nothing.
I'm sure other people have had this problem, as I'm trying to get into the Flash>Avenue zone can someone please help asap!
Many ta,
Nick Ronin