C# Editor Crashes Rhino

Hi All,

Anytime I open the C# editor in Grasshopper and attempt to start working it crashes Rhino with ''An unhandled Microsoft .NET Framework exception occurred in Rhino.exe [21228]''

System::AppDomain::CurrentDomain->UnhandledException event occured

SENDER: Name:DefaultDomain

There are no context policies.

EXCEPTION: System.ExecutionEngineException

MESSAGE: Exception of type 'System.ExecutionEngineException' was thrown.

SOURCE: 

CALL STACK

Can anyone shed some light on this?

Thanks in advance,

Ryan