We have a couple of suggestions to try if you encounter this error (which seems to be a very rare occurrence).
#1 : Remove Projects and Reboot
Close all projects and documents, the View | Projects panel should be empty.
Shut down CircuitStudio then reboot the computer.
Add back in a project and test the Layer Stack Manager.
#2: Repair .Net Framework
The Microsoft .Net components of Windows (for example, version 4.5.1) may require repairing.
To fix this, run the .NET Framework Setup Verification Tool available at http://blogs.msdn.com/b/astebner/archive/2008/10/13/8999004.aspx.
If the .NET Framework installation is available in the Windows Control Panel: Program and Features section, double click on the application, select to repair the .NET Framework to its original state. (This may not be available in newer versions of Windows).