How to close a C# application gracefully when crashes or end-process by task manager?

This C# application is a COM client & the COM server is C++ which runs as a Service. When C# client crashes or end-process, it doesn't call the COM object's destructor. So the Server keeps that object as a live one.
Any suggestion?

(If the client is closed gracefully, it calls the destructor of COM object. So the Server knows the object is no longer available.)