material appearing black in 3D viewport, material-view, blender internal

Hello blender users,
I am having trouble trying to create a scene for an OpenGL video render (set up in Blender Internal). Everything was going smoothly, until all of a sudden (randomly, as far as I could see) all the materials on my car model started acting like Cycles Materials being used in Blender Internal,
specifically:
-in Solid View: appearing normally
-in Material View: if not selected, solid black; if selected, solid yellow
However, there are differences between typical instances of this problem and the problem I seem to be having, which are:
-in Textured View: in typical Cycles-Material-In-Internal-Renderer instances, the object appears normally, whereas in my problem it acts just like it does in Material View
-in Rendered View: in Cycles-Material-In-Internal-Renderer instances, the material isn’t rendered at all, whereas in my problem it renders the material normally but without the textures.

(I tried attaching the blend file, but the attachment manager seems to try importing the files from my computer for a certain period of time and then give up with no explanation)

Observations I have made:
-The material render preview in the material panel shows the material working just fine.
-The image textures aren’t missing.
-The materials aren’t Cycles-based.
-The model is directly appended from another blend file I made it in, in which the materials show up fine (also Blender Internal, set up to be rendered the same way I’m trying to render this scene). If I append the model again from that blend file, the newly appended model shows up black as well, so it isn’t some change I made to the car object that is causing the problem. It seems to be specific to this blend file.
-The materials have two image textures; I have found that if I disable just one (doesn’t matter which one), the material shows up and behaves normally (though other objects with different materials that contain two enabled textures show up fine).
-Different objects that have the certain rebellious materials in question act the same way, so the problem isn’t object-specific.
-I have tried simply rebuilding the materials from scratch, copying the ones I wanted as best as I could; but at some point it just started acting the same.

I have guessed based on the above observations that the blend file isn’t reading the materials normally, though I haven’t been able to find where the change is. Another observation I have made, however, that goes against it being the fault of the specific blend file’s interpretation of the material, is that if I start a new blend file and append everything from the file I was formerly working in, it shows the same problem.

I really appreciate any help given, and apologize for the difficulty of trying to diagnose the problem without access to the file (and trying to keep up with my incredibly detailed account of the problem).

-Chris

(I tried attaching the blend file, but the attachment manager seems to try importing the files from my computer for a certain period of time and then give up with no explanation)
Not really a good reason for not supplying a blend file which you should be doing for ALL support questions.
Ensure you remove all crap from the file and use the compress option when you save the file to ensure it’s not too large. Alternatively post to one of the gazillion file host sites (google drive, one drive, dropbox etc etc etc) or a site specifically for blend files http://www.pasteall.org/blend/