Hi

I was just looking at your mesh and it explains why you are getting the problems you are getting. You have a lot of non manifold geometry in there. It looks to me like you started with a sphere for the top and tacked on the bottom piece. Your net getting the result you want in smooth preview because your edge flows are not fluid. You can see that once your edge flows reach the brow of the helmet they break of and are spread elsewhere through the bottom half of the helmet. Also you should really try to keep all your faces of similar size when modelling to make things easier for you when you texture and also to stop those artefacts your getting on your helmets cheeks. The smooth preview is pulling the geometry out of shape as there is not enough geometry in the lower portion of the helmet. I would suggest you start with a cube when modelling this helmet and concentrate on edge flow and face size.