Well for une,
#include <string>
#include <vector>
</vector></string>
have been included twice, first in the header file, "ConnectedComponent.h", then again in the implementation file "ConnectedComponent.cpp".
And in the following, I'm reasonably sure that iostream is in there somewhere:
namespace AWF {
using namespace System;
using namespace System::ComponentModel;
using namespace System::Collections;
using namespace System::Windows::Forms;
using namespace System::Data;
using namespace System::Drawing;
But the real issue IS:
#include <vector>
#include <iostream>
#include "ConnectedComponent.h"
#include <string>
using namespace std;
AS YOUR WARNINGS listed these four #include statements, it is telling you that they have ALREADY BEEN INCLUDED IN YOUR StdAfx.h file . . .