Problem: The ribbon interface in ArcGIS for AutoCAD build 250 does not load
The ribbon interface in ArcGIS for AutoCAD fails to load when the NETLOAD command is issued and the ArcGISforAutoCAD.dll is referenced.
AutoCAD 2010 and 2011 are set to use the 'Classic' workspace. The 'Classic' interface is unable to make use of ribbon-style menus.
Solution or Workaround
Switch from the 'Classic' workspace to the '2D Drafting and Annotation' or '3D Modeling' workspace by going to Tools > Workspaces, and selecting the desired Workspace.