Microsoft.Expression.Drawing.Aero missing (what is it?!)

Question

I have a window and I created a "callout" there. When I try to create the new window with this.InitializeComponent(); I get an exception:

The assembly with display name 'Microsoft.Expression.Drawing.Aero' failed to load in the 'Load' binding context of the AppDomain with ID 1. The cause of the failure was: System.IO.FileNotFoundException: Could not load file or assembly 'Microsoft.Expression.Drawing.Aero, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The system cannot find the file specified.

How can it be? What is Microsoft.Expression.Drawing.Aero?

Answer 1

The solution can be delete your .suo file and ReBuild your entire solution.

The *.suo file is found in the project root folder.(If you can't see your *.suo file be sure you have configured the windows explorer to see hidden files.)