I seem to be having a similar problem here.
I instantiate a ServicedComponent inside my class and assign it to an
instance variable, and get an InvalidCastException pointing to a
completely unexpected class. Something like this:

Class2 : ServicedComponent, IInterface
{
}

Class1 : ServicedComponent
{
IInterface obj;

public myMethod ()
{
  obj = new Class2();   // This is where I get the exception.
}
}

The exception I get is:
InvalidCastException: Expected Class2, recieved Class1.

I find it very strange for several reasons:
1) Why would it receive Class1, since this code is called INSIDE
Class1?
2) It says "Expected Class2", even though my instance member is
defined as IInterface, not Class2.
3) All this happens in my testing environment, but not in the
development environment. Same DLLs, theoretically.

All this code is server-code being called by Remoting with another
Facade layer calling the Class1 first, just in case it matters.

Hope I was understandable, and I hope this gets clarified.

TIA,
  Avner Kashtan