Dunno. Never had that happen before. Check you camera angle and lighting. You can change the color of the background, using the tab. As far as the silhouette... like I said, never had that happen. 

I know the latest D|S uses needs abit more system requirements than older versions, so check your system by using the pulldown D|S System info. It'll let you know if your computer can use it's built in shaders.

-- Jeff