i upgraded from 2010 to 2011 and noticed one minor problem:
Dim pref As AcadPreferences = Autodesk.AutoCAD.ApplicationServices.Application.Preferences
this line throws exception, that i have attached
the issue is, that after installing Civil 2011, libraries in Autodesk Shared directory were replaced with the new ones and somehow 2010 can't hande this
with the old 2010 dlls, this code was fine, also on 2011 this code works good, problem only occures, when i use the build with 2011 references on AutoCAD 2010
They broke some things in 2011. If I remember correctly something was wrong with with 2011 installer and 2010 interop dll's but is supposed to be fixed in update1 but I have not seen any update's for the vertical's