Motion tracked objects don't render properly(?)

Noob question here — I just tried using the motion tracker for the first time, and the tracking itself works well. However, any objects I add to the scene seem to lack shading, or sometimes consist of just the shading without any object(?). This happens with newly created, un-modified objects and lamps. See the attached picture for a comparison between the 3d view and rendered image. I haven’t used Blender much, so the solution is probably something really simple, but I can’t figure out how to render solid, shaded objects. Please help! (I’m using Blender 2.70).