DWORD derr = GetLastError();
derr = derr;
LPVOID lpMsgBuf;
FormatMessage( FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS, NULL, GetLastError(), 0, // Default language (LPTSTR) &lpMsgBuf, 0, NULL ); // Process any inserts in lpMsgBuf.
// ...
// Display the string.
AfxMessageBox((LPCTSTR)lpMsgBuf);