Static lib question

This is the first time I've worked with static libraries and I ran into a little problem, heres the code:

libTest.h

Code:

---

#ifndef __LIBTEST_H__
#define __LIBTEST_H__

#if _MSC_VER > 1000
#pragma once
#endif

#pragma warning(disable: 4996)

#include <string>

using namespace::std;

class CTest
{
public:
        CTest(void);
        ~CTest(void);

        int Test();

private:
        string m_sTest;
};

#endif

---

libTest.cpp

Code:

---

#include "libTest.h"

CTest::CTest(void)
{
        m_sTest = "";
}

CTest::~CTest(void)
{

}

int CTest::Test()
{
        return m_sTest.size();
}

---

When I include/link to the libTest library on an application that already includes <string>, I get:

1>msvcprtd.lib(MSVCP80D.dll) : error LNK2005: "public: __thiscall std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >::~basic_string<char,struct std::char_traits<char>,class std::allocator<char> >(void)" (??1?$basic_string@DU?$char_traits@D@std@@V?$alloc ator@D@2@@std@@QAE@XZ) already defined in Main.obj

How can I get rid of this problem? My library makes uses of strings/vectors/maps and so on and they all cause 'multiply defined symbol' errors.

Thanks in advance for any help.

Anyone have any idea?
I've been looking through example static library sources, but none of them seem to use the stl library.

Make sure your lib and your project that uses the lib match in their runtime library linkage. (Under project settings, C/C++ -> Code Generation -> Runtime Library )