Parts saved before UGS changed the color map (NX3?) will come in the "wrong" color, since the color map in the newer assembly file is different.
Per John Baker, on the UGS newsgroup:
"What the problem is, is that your assembly file is using a new (NX 3
defaulted) CDF file, while your part files are still based on the old pre-NX
3 colors. You have two choices, either change your assembly file so that it
uses the old CDF (we still supply it with NX 4, just that it's no longer the
standard) or you have to replace the old CDF with a new one as well as edit
the colors of the objects (Solids, Surfaces and Curves) in your component
part files.
You can change the CDF files under Preferences/Visualization... under the
'Color Palette' tab. As for editing the colors of the objects in your
existing parts, you can use the GRIP program that I've created for this
purpose (I've attached a zip file that contains both the source code and a
Windows executable version of the program)."
-Dave
Everything should be designed as simple as possible, but not simpler.