Using vector as class member lead to Data Abort error

Hi, I'm coding on windows mobile 6 and I have meet a strange problem,
which I have already tried to Google it, but still cann't work it out.
here is my problem:

there is a class with a vector as member as below:
code:
/**********MyTest.h****************/
#pragma once
#include <string>
#include <vector>

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

private:
        vector<string> m_vecString;

};

/*****************************/

and I also have a dialog class as below,which has CMyTest class
object:
/**************Mobile_Test**************/
// Mobile_TestDlg.h

#pragma once
#include <iostream>
#include <fstream>
#include "InfoDlg.h"
#include "MyTest.h"

#define WM_MSGWHITSTR (WM_USER+193)

class CMobile_TestDlg : public CDialog
{
public:
        CMobile_TestDlg(CWnd* pParent = NULL);

        enum { IDD = IDD_MOBILE_TEST_DIALOG };

        protected:
        virtual void DoDataExchange(CDataExchange* pDX);

protected:
        HICON m_hIcon;

        virtual BOOL OnInitDialog();
#if defined(_DEVICE_RESOLUTION_AWARE) && !defined
(WIN32_PLATFORM_WFSP)
        afx_msg void OnSize(UINT /*nType*/, int /*cx*/, int /*cy*/);
#endif
        DECLARE_MESSAGE_MAP()

        /*================Data====================*/

public:
        BYTE m_sharedDataArray[521];
private:
        CMyTest m_test; //!!!!

public:
        static UINT Reader(LPVOID pParam);
        static UINT Writer(LPVOID pParam);

public:
        afx_msg void OnBnClickedButtonOk();
        LRESULT OnMsgwithStr(WPARAM wParam, LPARAM lParam);
public:
        afx_msg void OnBnClickedButtonTest();

};

/****************************/

this program compiled fine, but when I run it on Debug mode, I get
error as below:

Platform Type : PocketPC
Data Abort: Thread=97b0aa40 Proc=8c3e89e0 'Mobile_Test.exe'
AKY=00400001 PC=00018c38(Mobile_Test.exe+0x00008c38) RA=0001981c
(Mobile_Test.exe+0x0000981c) BVA=2e29f8f9 FSR=00000001
Unhandled exception at 0x00018c38 in Mobile_Test.exe: 0x80000002:
Datatype misalignment.

and this error seems to happen in the constructor of CTest. because
when I run it step by step, it turns out the error is happened at :
/************xutility.h*******************/
__CLR_OR_THIS_CALL _Container_base()
                : _Myfirstiter(0)
                { // construct childless container
                }
/****************************/

I have no idea why this error happened, Any assistance would be
appreciated.

Thx