Are you having trouble with missing icons on your Civil 3D Transparent Commands toolbars?
Seth Hall posted a great article on how customizing your CUI can affect this behavior, and what to do to get it back into shape.
The File Names and the Problem
The C3D.DLL and C3D.MNR file contain the icon information pertaining to the Ribbon and the Transparent Commands and Transparent Command Filters toolbars. If Civil 3D is using a CUI file named something other than C3D.CUIX then you may have problems. These files need to have the same naming convention as the CUIX file in use.
Vista Roaming profile Path = C:\Users\<<USER NAME>>\AppData\Roaming\Autodesk\C3D 2010\enu\Support
If the DLL and the CUIX are named the same, the application will rebuild the MNR, and restore the interface icons, except the Toolbar icons.
When you are gathering and renaming files, ensure that he original MNR file is copied and named the same as the DLL and new CUIX file. Once in place, Civil 3D will load and use the toolbar icons in the original MNR file.
Thanks to Seth Hall and Being Civil for this article.