Troubleshooting a misbehaving designer in Visual Studio 2010
Published by Marco on   Anyone who’s used Visual Studio 2010[1]
for a non-trivial Windows Forms project has run into situations
wherein the designer can no longer be opened. Usually, it’s
because the class encounters null-reference exceptions when
referencing data that is unavailable until runtime. Those are
easy to fix: just avoid referencing that data in the constructor
or load-routine while in design-mode.  However, sometimes Visual
Studio has problems loading assemblies that it seems it should
have available. Sometimes Visual Studio seems to have a devil of
a time loading assemblies whose location it has quite explicitly
been told.  If you like, there is a walkthrough—with
screenshots!—at the end of this article, which shows how to
solve even the most intractable designer problems.  A Tale of
Two Platforms  One of the troubles is that many developers have
moved to 64-bit Windows in order to take advantage of the higher
RAM limits. The move to 6