It replaces the entry-point with the "unmanaged" entry in CWinApp, which correctly initialize the CRT/MFC/ATL.

1. Change the "entry point" in you linker settings from "main" to "wWinMainCRTStartup"
2. Add "#include <afxwin.h>" to your "stdafx.h"
3. Replace your "main" method with the following:
class CMFCApp : public CWinApp
virtual BOOL InitInstance()
    // Enabling Windows XP visual effects before any controls are created
    // Create the main window and run it
    Application::Run(gcnew Form1());
    return FALSE;
} theApp;