Solution to "Microsoft.Silverlight.Csharp.Targets" was not found error in Visual Studio

Try the following if you get this error in Visual Studio:

The imported project "C:\Program Files (x86)\MSBuild\Microsoft\Silverlight\v4.0\Microsoft.Silverlight.CSharp.targets" was not found. Confirm that the path in the <Import> declaration is correct, and that the file exists on disk. 

1. Uninstall all versions of Silverlight (not sure if this is required, but I was getting issues when I tried to install SilverLight 4)

Add/Remove Programs –> Search for Silverlight—> Uninstall

2. Install the Silverlight 4 SDK

3. Go back to visual studio and reload the project.

That resolved the issue for me.