Оформил: DeeCo
Автор: http://www.swissdelphicenter.ch

 function GetLastErrorText(): string;
 var
   dwSize: DWORD;
   lpszTemp: PAnsiChar;
 begin
   dwSize := 512;
   lpszTemp := nil;
   try
     GetMem(lpszTemp, dwSize);
     FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM or FORMAT_MESSAGE_ARGUMENT_ARRAY,
       nil,
       GetLastError(),
       LANG_NEUTRAL,
       lpszTemp,
       dwSize,
       nil)
   finally
     Result := lpszTemp;
     FreeMem(lpszTemp)
   end
 end;