So I completely uninstalled all Silverlight and Silverlight SDKs on my machine, and have reinstalled Silverlight and the Silverlight 4 SDK and Silverlight 5 SDK. This has resolved the originally posted error.
I pulled down the src files and attempted to build the Caliburn.Micro.sln project on my machine. I receive numerous errors from various files concerning the System.Windows.Interactivity namespace. I have verified that I have the Microsoft Expression
Blend SDK for .NET 4 installed - and the dll that contains that namespace exists at:
C:\Program Files (x86)\Microsoft SDKs\Expression\Blend\.NETFramework\v4.0\Libraries\
Should I be able to download and build the caliburn code or do I need to manually add all the necessary references?