Here is the model: https://p3d.in/g7qa3
Problem: there is a vertex color applied to the middle ship’s mesh. It came after I added the first material (the windows texture/material).
More information: - I am using Cycles Render and UV mapping is done there; - Ship is black, because the first material texture I added has black and white contents; - When I first load a material, it seems to color the mesh in a random hue from its own color content; - I have not used anything else (like vertex painting and such), all color diffusions are set to white as default;
How do I remove this nasty vertex coloring, while keeping my UV map and materials intact?
just seeing the mesh doesn’t help us at all to understand what may be happening. Please share the blend file!
http://blend-exchange.giantcowfilms.com/b/2377/
Here it is…
The textures themselves will be missing, but the awful cyan coloring of the untextured bit of the mesh (the ship in the middle) should still be there.
I can’t find anything wrong with your scene 
(well, the only thing was just the ‘z_blank’ material, which has a color with 0.0 alpha in the diffuse node… Anyway, alpha values are discarded, so setting them up makes no difference)
There’s a vertex color layer in the «ns_main_frame_new» object, but all vertices are painted pure white, and they are not influencing anything.
That checked, you may want to try the scene with another blender version, or maybe check your graphic card settings. (or the problem is with the textures, but by your description in the first post, it doesn’t look like it)