Handling wh_shell's window destroy message

i have written application for WH_SHELL and WH_CBT hooking,the problem with this application is that i'm able to hook window created messages but for window destroy messages my application just crashes,if i comment the window destroy code the application works fine,i have google it and found no solution.My ultimate concern is how can i handle window destroy message in this application.Posting the necessary code snippet below
this is my hooking dll

LRESULT CALLBACK HookProc (int nCode, WPARAM wParam, LPARAM lParam )
{		        
	if (nCode == HCBT_KEYSKIPPED && (lParam & 0x40000000))
	{        
		
	}
	else if (nCode == HCBT_SETFOCUS)
	{
		::PostMessage(g_hSpyWin, MSG_MY_WM_SETFOCUS, wParam, lParam);
	
	}
	else if(nCode==HSHELL_WINDOWCREATED)
	{
		::PostMessage(g_hSpyWin,MSG_MY_WM_ACTIVATE,wParam,lParam);
	}
	else if(nCode==HSHELL_WINDOWDESTROYED)
	{
		::PostMessage(g_hSpyWin,MSG_MY_WM_DESTROY,wParam,lParam);
	}
	return CallNextHookEx( 0, nCode, wParam, lParam);
}

this is my main function,here i call another function OnNewCreateWindow() which does nothing but writes information about created window into file.

LRESULT OnNewWindowCreate(WPARAM wParam,LPARAM lParam)
{
	
	thwnd=(HWND)wParam;
	OnNewCreateWindow1(thwnd);
	return S_OK;
}

LRESULT On_WindowDestroy(WPARAM wParam,LPARAM lParam)
{
	dHwnd=(HWND)wParam;
	MessageBox(NULL,"Into destroy window function","Destroy",MB_OK);
	//OnWindowDestroy1(dHwnd);
	return S_OK;
}
LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
	if (message == MSG_MY_WM_KEYDOWN)
		return OnInterceptKeyStroke(wParam, lParam);

	if (message == MSG_MY_WM_SETFOCUS)
		return OnSetKeyboardFocus(wParam, lParam);

	if(message==MSG_MY_WM_ACTIVATE)
		return OnNewWindowCreate(wParam,lParam);

	if(message=MSG_MY_WM_DESTROY)
		return On_WindowDestroy(wParam,lParam);
		

	switch (message)
	{	
	case WM_DESTROY:
		PostQuitMessage(0);
		break;
		
	default:
		return DefWindowProc(hWnd, message, wParam, lParam);
	}
	return 0;
}

Here in the destroywindow function i have entered a messagebox() when i execute the application it just shows the messagebox twice and then exists the application.i dont know where i'm going wrong or what should i do more to handle the destroy window msg,same happens if i use

Tags: C++, DLL, Hooking