This happened to me in college. Apparently maya looses connection to materials sometimes (..wut?).Ok this might have been a mistake on my part, I dont think its the normals anymore, both sides of many of the faces are not visible so it cant just be that they are faceing the wrong way.
Ill give more information after I try a few things, the faces could be hidden but I dont see why.
It was that the material had ditached itself from some of the faces, just applied a new one and its fine now, dont know why the material was detached.
Use the paper-clip (Fonts | Sizes | A | | paper clip) to upload an attachment.btw Can I not insert an image without bringing it in from a url?