I've a remoting server and client:
the client calls a method at the server:
public class ExceptionClass : MarshalByRefObject
{

public void CreateException ()
{
Form1 f = new Form1(); // Form1 is just an empty
windows.forms.form
f.ShowDialog();
}

}

When CreateException is called, an exception is thrown
System.InvalidOperationException

I have tried this with both versions dot framework 1.1 and 2.0.
The problem only occurs with framework 2.0.

A Tcp channel is used for transportation

If needed I can provide a simple test project with all remoting config files.