If you move or copy a toolbar from one .cui file to another, the toolbar icons may not appear correctly in the new CUI. To work correctly, the .dll file that contains the toolbar bitmaps must have the same name as the .cui file.
For example, if you move or copy a toolbar from civil.cui to custom.cui, you must make a copy of civil.dll and name it custom.dll. These bitmap .dll files are located in the same folder as the .cui files: C:\Documents and Settings\<your login name>\Application Data\Autodesk\C3D 2007\enu\Support.