Whooh! Ok, it looks like the segment is not reading the "D" textures. Be sure to check all segments and entities you use in the level. I have come across a similar problem. I discovered that when using the tangent basis shader, "all" objects that are assigned a shader, has to have "All" the proper textures needed for that shader, and assigned properly. If not (if even one object is not asigned properly) it can cause strange anomolies like this one.
Start by checking the directory path of assigned textures of all objects used, and be sure you have the complete set(D,D2,N,I) in the proper directory for the segments. And check all your entities as well. I'm pretty sure there is something in your level that is not assigned properly, is in the wrong place, or is missing a texture.
2.5ghz QuadCore,4gb ram,1gb ATI graphics. Dual OS. WinXP, Win7.