Okay first of all. Why oh why are you using sun and physical sky? it doesnt help but confuse the issue when you have probs.
If in doubt kick all lights out. Replace with one singular directional light......turn on mental ray, but dont even worry about fg or global ill right now, keep it simple. As for shaders etc. Just put one blinn over the models. Dont worry about a lambert. Then on the shader put reflection and spec to zero and render it and see what happens. If it okay then start to add back the textures one at a time on a new shader for each building, again keeping the reflection and spec off on each shader.
if not zip the scene up and post it, I'll have a look...its gonna be something ridiculous and simple -especially if you got it off turbocraps website. the problem with that place they need a qc. Something they claim to have but dont.
Jay
Thats it, I completely forgot it existed and as soon as I remembered, I managed to solve the problem.Yeah that'll be it.
For the future though, if you are unsure what material is on the object, simply select the model and go to the hypershade and graph materials on selected objects. This will show you what is actually attached to the model, so you can try to sort it and know what is going on before posting for help as we can only hazard a guess here without seeing the scene firsthand. Also use the maya help on materials assignment. Alot of people forget its there....
Jay