I'm a newbie to Blender. First, thanks to all that help novices. I'm learning Blender Internal first.
My first project was to merge two existing shared blender files: first was an animation of 600 frames (20th Century Fox Intro). Then I imported shared 3D automobile objects. The merged scene (in 4 layers) looks fine in solid, material and even rendered VIEWS. But when I render the camera image (in BI or even in Cycles), the top half of the 3D scene is gray. Seems I have a solid gray plane (just above my grid plane) cutting off the image. But there is no plane object there. See my screen capture slice below.
I'm on a 2009 iMac with ATI Radeon HD Graphics (512MB), 3.06GHz Core 2 Duo CPU and 16GB of RAM. Couldn't find a similar reported problem here or on the web.