为什么会有这个错误？

[hncdsun]

d:\program files\microsoft visual studio\vc98\mfc\include\afxv_w32.h(14) : fatal error C1189: #error : WINDOWS.H already included. MFC apps must not #include <windows.h>

[hncdsun]

我在stdafx.h中加入下行就出现这个问题 ！！！
#import "c:\program files\common files\system\ado\msado15.dll" no_namespace rename("EOF","adoEOF")

[hncdsun]

我找到了，
如下定义不会出错！
//

#if !defined(AFX_STDAFX_H__0C2C9889_DE8A_11D5_A752_5254AB1C4FEF__INCLUDED_)
#define AFX_STDAFX_H__0C2C9889_DE8A_11D5_A752_5254AB1C4FEF__INCLUDED_

#if _MSC_VER > 1000
#pragma once
#endif // _MSC_VER > 1000

#define VC_EXTRALEAN // Exclude rarely-used stuff from Windows headers

#include <afxwin.h> // MFC core and standard components
#include <afxext.h> // MFC extensions
#include <afxdisp.h> // MFC Automation classes
#include <afxdtctl.h> // MFC support for Internet Explorer 4 Common Controls
#ifndef _AFX_NO_AFXCMN_SUPPORT
#include <afxcmn.h> // MFC support for Windows Common Controls
#endif // _AFX_NO_AFXCMN_SUPPORT
#import "c:\program files\common files\system\ado\msado15.dll" no_namespace rename("EOF","adoEOF")

//{{AFX_INSERT_LOCATION}}
// Microsoft Visual C++ will insert additional declarations immediately before the previous line.

#endif // !defined(AFX_STDAFX_H__0C2C9889_DE8A_11D5_A752_5254AB1C4FEF__INCLUDED_)

但这样会出错：
//

#if !defined(AFX_STDAFX_H__0C2C9889_DE8A_11D5_A752_5254AB1C4FEF__INCLUDED_)
#define AFX_STDAFX_H__0C2C9889_DE8A_11D5_A752_5254AB1C4FEF__INCLUDED_

#if _MSC_VER > 1000
#pragma once
#endif // _MSC_VER > 1000
#import "c:\program files\common files\system\ado\msado15.dll" no_namespace rename("EOF","adoEOF")
#define VC_EXTRALEAN // Exclude rarely-used stuff from Windows headers

#include <afxwin.h> // MFC core and standard components
#include <afxext.h> // MFC extensions
#include <afxdisp.h> // MFC Automation classes
#include <afxdtctl.h> // MFC support for Internet Explorer 4 Common Controls
#ifndef _AFX_NO_AFXCMN_SUPPORT
#include <afxcmn.h> // MFC support for Windows Common Controls
#endif // _AFX_NO_AFXCMN_SUPPORT


//{{AFX_INSERT_LOCATION}}
// Microsoft Visual C++ will insert additional declarations immediately before the previous line.

#endif // !defined(AFX_STDAFX_H__0C2C9889_DE8A_11D5_A752_5254AB1C4FEF__INCLUDED_)