@danlisa
Oops, I forgot to thank you for yr tip.

Shame on me.
Many thx for your help!!
@HW3
Is this an "only-GWX-problem"?
Now I've checked all pics, I think it's the int_halo.tga that causes the problem. But I still think, you can find the solution in the configuration of embedded images in a single dat-file - perhaps in the folder "library". I hope some ship modders can help.
Here is a very detailed pic of the texture:
http://img862.imageshack.us/i/sh3img...131953724.jpg/
Tom