I stumbled onto what I would consider a bug in the Visual Studio 2005 IDE today. The issue came about after I rebuilt due to renaming a type that was used in a user control. After building I got an error when I attempted to load the user control in design mode. The error was:
Could not find type 'TypeName'. Please make sure that the assembly that contains this type is referenced. If this type is a part of your development project, make sure that the project has been successfully built.
The variable 'ControlName' is either undeclared or was never assigned.
It turns out that I had the assembly that was being built in the IDE also in the GAC. It needed to be in the GAC for testing that I was doing outside of the IDE. The problem went away after I uninstalled the library from the GAC.
I understand why the problem occurs, but in my opinion Visual Studio should not perform the normal assembly resolution -- especially when the type is internal to the project like it was in this example. Anyway, hopefully, this will help someone else out.