C++ COM client releases two different objects within one call ?! 2nd Release causes access violation

Question

I have the weirdest problem, and most likely there is something I am missing or I don't know.

I created a C# COM interface/class that for this question we'll call it: Ics_obj and Ccs_obj. In the destructor of the object I added a trace to the output debug:

~Ccs_obj()
{
    OutputDebugString("Releasing: "+this.GetHashCode()); // OutputDebugString with p/invoke
}

That I wrote a C++ class that Ics_obj is a member in that class, and the member is the com_ptr_t wrapper of Ics_obj generated in the .tlh:

class lib_exp_macro cpp_client
{
public:
 cpp_client();
 ~cpp_client();
 ...
 ...
 Ics_objPtr _csobj; // the Ics_obj* wrapped in com_ptr_t.
}

In the constructor I create an instance of Ccs_obj, and in the destructor I release it. I also added the following traces:

cpp_client::cpp_client()
{
  HRESULT hr = _csobj.CreateInstance( __uuidof( Ccs_obj ) );
  if(FAILED(hr)){ /* throw exception */ }
  OutputDebugString("Creating client");
}

cpp_client::~cpp_client()
{
  OutputDebugString("before releasing _csobj");
}

---

Now, I have created 2 instances of cpp_client through my code (creating them with the same thread during initialization of my application), and I get 2 traces of "Creating Client".

The problem is that during shutdown I get ACCESS VIOLATION and the traces are as follow:

before release // first object being released
Releasing: (some number X)
Releasing: (some number Y, Y != X) // <- where did that come from?
before releasing _csobj
SYSTEM CRASH HORRIBLY WITH ACCESS VIOLATION! :-(

When I debug I get ACCESS VIOLATION for accessing the v-table of the COM object.

Does anyone know why I get ACCESS VIOLATION? what am I doing wrong? I am REALLY LOST HERE! :-(

Thanks in advance!

UPDATE:

With the help of two answers (that were deleted), I understood more things, but I still have open questions...

First and the most important thing is that the 2nd release was in dllmain PROCESS_DETACH. When I moved the release code out of this context, everything was fine, but why can't I release the COM object in the PROCESS_DETACH context?!

One of the answers that were deleted said that CLR of the .Net has shutdown, therefore the 2nd release in my traces. This made a lot of sense and what lead me into moving the releasing code out of PROCESS_DETACH context, but if it is so and CLR does shutdown because the PROCESS_DETACH code, why don't I get any of the "Releasing: ..." traces if I'm not releasing the COM object (by detaching _com_ptr_t)??? Or in other words, why does CLR doesn't shutdown if I don't release the 1st object?

Thanks again for your amazing help!