Hi

Based on my experience, the COM client -->CCW-->.NET code.
But the CCW will not call the dispose on the .NET library automatically,
also the Finalizer queue(i.e. the deconstructor of .NET class) is managed
by GC, it took the responsibility to handle the release issue.

So for now,  I suggest you implement the IDisposable interface on your .net
class and call the dispose explicitly in your com client to do the release
the necessary resource.
using System;
using System.Diagnostics;
using System.Runtime.InteropServices;
namespace DecntorComServer
{
    [ClassInterface(ClassInterfaceType.AutoDual)]
    public class MyClass : IDisposable
    {
        public MyClass()
        {
            Debug.WriteLine("MyClass Constructor");
        }
        public void TestCall()
        {
            Debug.WriteLine("Call in");
        }
        ~MyClass()
        {
            Debug.WriteLine("MyClass DeConstructor");
//We will see that even use the class in managed code, we still need to
call GC.Collect() to enable the Finalize/deconstructor
//Also we did not recommend call GC.Collect ourselves, because that may
lead to performance hit.

        }
        #region IDisposable ³ÉÔ±

        public void Dispose()
        {
            Debug.WriteLine("Calling Dispose");
        }

        #endregion
    }
}

Best regards,

Peter Huang
Microsoft Online Partner Support