1.查一下m_pszAppName是否有被修改
2.看下紧接着是否有这样一句代码：
AfxGetModuleState()->m_lpszCurrentAppName = m_pszAppName;
没有的话加上就好。
修改AppName很多人参考MSDN，可MSDN上的例子有缺陷！
原因大概如下：
m_pszAppName与m_lpszCurrentAppName未保持一致造成的。查看MFC源码，在程序最开始AfxWinInit中调用CWinApp::SetCurrentHandles，其中有一句pModuleState->m_lpszCurrentAppName = m_pszAppName，因此两个指针必须保持一致。
软件在InitInstance中设置了m_pszAppName，未同时修改m_lpszCurrentAppName，free(m_pszAppName)后造成m_lpszCurrentAppName内存无效，成为野指针。
MessageBox在弹框时如果未传入标题，则会使用AfxGetAppName作为标题名，而AfxGetAppName返回的是m_lpszCurrentAppName，此时该指针指向的内存已经失效，导致了标题乱码。
参考文章：https://blog.csdn.net/wdsswadjsn/article/details/3220338
摘录如下：
As far as I understand, the MSDN documentation regarding how to change
CWinApp::m_pszAppName is incorrect. Following the documentation can lead to
memory access violation errors. Additionally, the KB article 154744 also
gives wrong advise about how to change m_pszAppName.
Here's why:
At the very beginning of application initialization, AfxWinInit calls
CWinApp::SetCurrentHandles, which caches the current value of the
m_pszAppName pointer as follows:
pModuleState->m_lpszCurrentAppName = m_pszAppName;
That is, the module state struct holds a copy of the m_pszAppName pointer.
Now, if you change m_pszAppName in InitInstance as adviced in MSDN, you
still have the old pointer value in pModuleState->m_lpszCurrentAppName. The
AfxGetAppName() function returns AfxGetModuleState()->m_lpszCurrentAppName.
Many times replacing m_pszAppName does not lead into problems because
_tcsdup will return the same pointer value as before. But of course, the
pointer value can be different, and if it is, it can lead into a crash later
when someone is calling AfxGetAppName().
For example, the following code in InitInstance is almost certain to fail
because the app name is relatively long and causes _tcsdup to return a
pointer value that is different than before:
free( ( void* )m_pszAppName ); m_pszAppName = NULL;
m_pszAppName = _tcsdup(
"ABCABCABCABCABCABCABCABCABCABCABCABCABCABCABCABCABC" );
const TCHAR* ptsz = AfxGetAppName();
_ASSERTE( lstrcmp( ptsz, m_pszAppName ) == 0 ); // TYPICALLY FAILS
Now, my question is: Can Microsoft fix the buggy documentation? And, what is
the correct way of changing m_pszAppName. Is the following safe in
InitInstance:
free( ( void* )m_pszAppName ); m_pszAppName = NULL;
m_pszAppName = _tcsdup( "<new name>" );
AfxGetModuleState()->m_lpszCurrentAppName = m_pszAppName;