vc程序退出报错！

int CTaskBarDlg::OnCreate(LPCREATESTRUCT lpCreateStruct)
｛   ......
    m_ptoolBar->Create(IDD_TOOLBAR,this);
    m_ptoolBar->ShowWindow(SW_SHOW);
    m_pdatagram->Create(IDD_DIALOG_VIEW,this);
    return 0;
}
void CToolBarDlg::OnExit()
{   
    ::SendMessage(GetParent()->m_hWnd,WM_CLOSE,NULL,NULL);
    DestroyWindow();
}
void CTaskBarDlg::OnClose()
{
    m_pdatagram->SendMessage(WM_DESTROY,NULL,NULL);
    delete m_ptoolBar;
    delete m_pdatagram;
    CDialog::OnClose();
}
退出时程序会报错，程序中有一个全局线程。