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Derived Class Error

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I have a class that wraps the windows message handler and creation routines and it uses this function to create a window:
void CWND::CreateWnd(HINSTANCE instance)
{
  DWORD		   dwExStyle;
	DWORD		   dwStyle;
	HWND       hwnd;
  WNDCLASSEX wc;
  
  RECT windowRect;
	windowRect.left   = (long)0;
	windowRect.right  = (long)m_width;
	windowRect.top    = (long)0;
	windowRect.bottom = (long)m_height;
   
  // Setup the windows class
  wc.cbSize          = sizeof(WNDCLASSEX);
  wc.style           = CS_HREDRAW | CS_VREDRAW;
  wc.lpfnWndProc     = CWND::MessageRouter;
  wc.cbClsExtra      = 0;
  wc.cbWndExtra      = 0;
  wc.hInstance       = instance;
  wc.hIcon           = LoadIcon(NULL, IDI_APPLICATION);
  wc.hCursor         = LoadCursor(NULL, IDC_ARROW);
  wc.hbrBackground   = (HBRUSH)GetStockObject(BLACK_BRUSH);
  wc.lpszClassName   = m_className;
  wc.hIconSm         = LoadIcon(NULL, IDI_WINLOGO);  
  
  // register the class
  if (!RegisterClassEx(&wc))
  { 
    MessageBox(NULL, "Class Registration Failed!", "ERROR!", MB_OK | MB_ICONEXCLAMATION); 
  }
  else
  { 
    // save the class
    m_wndClass = wc;
  }
	
	if(m_fullscreen)
	{
	  BeginFullscreen(m_width, m_height, m_bpp);
    dwExStyle = WS_EX_APPWINDOW;
		dwStyle = WS_POPUP;	
	}
	else
	{
    dwExStyle = WS_EX_APPWINDOW | WS_EX_WINDOWEDGE;
		dwStyle = WS_OVERLAPPEDWINDOW;
	}
	 
	// Adjust Window To True Requested Size
	AdjustWindowRectEx(&windowRect, dwStyle, FALSE, dwExStyle);
 
  // Create the window
  hwnd = CreateWindowEx(dwExStyle, m_className, m_className, dwStyle | 
    WS_CLIPSIBLINGS | WS_CLIPCHILDREN, 0, 0, m_width, m_height, NULL, NULL, 
      instance, this);                     
  
  // Check to see if window creation failed
  if(!hwnd)
  { 
    MessageBox(NULL, "Window Creation Failed!", "ERROR!", MB_OK | MB_ICONEXCLAMATION); 
  }
  else
  { 
    // Show and update the window
    ShowWindow(hwnd, SW_SHOW);
    SetForegroundWindow(hwnd);
    SetFocus(hwnd);
    UpdateWindow(hwnd);
  }
  
  // store instance
  m_instance = instance;
}
However, when I create a child class that inherits the class CWND and attempt to embed this in a function it crashes and/or seg-faults. Here is a sample derived class like the one I am attempting to use:
class Test : public CWND {
  public:
    Test(LPCSTR className, int width, int height, int bpp, bool fullscreen) :
      CWND(className, width, height, bpp, fullscreen) {}
    
    void Blah(HINSTANCE instance)
    {
      CreateWnd(instance);
    }
};

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