Things that annoy me about C# - interfaces

Interfaces are great, I love 'em. What I don't like is C#'s restriction on the implementation of interfaces. Implementations must be either public (okay), or private using the "interface.method" syntax (okay), but what about protected? I want to be able to do the following, but I can't:

public interface IMyInterface
{
 void SomeMethod();
}

public class Class1 : IMyInterface
{
 // This causes a compile error
 // saying class does not implement interface!!!
 protected virtual void SomeMethod()
 {
  // do stuff
 }
}

public class Class2 : Class1
{
 protected override void SomeMethod()
 {
  // do other stuff
 }
}

You can do this in VB.NET, why not C#?