Surfaces are black and I dont know why :/

[avesthefox]

So what does it usually mean when a surface goes black like this? I cant seem to change it so I am assuming its an error in the model that needs adjusting?

Generally this seems to happen after performing boolean stuff in AC3D, or importing it from Blender after doing some very complex boolean stuff over there that AC3D cant seem to handle (I use AC3D mainly for very simple primitive boolean commands). :P