Modelling or rendering problem?

Im making model of my mobile phone. It is not finished yet, but when rendering it makes ugly faces as you can see. Tried to remove doubles and recalculate normals, but it dint help. Im using blender 2.5. What may cause that ugly render?
Attached render and edit mode picture too.


Doubled faces. From the edit mode image, it looks as if you have two completely separate but almost-coincident surfaces around the whole of the near end of the phone. Delete one of them.

Best wishes,

Thank You. That was the problem. Dont even know how I managed to do doubled faces.