关于一个Excel Com组件的问题（比较难）

客户端设计器：采用C#将Excel组件嵌入窗体中，确切的是将Excel单元格区域窗体进行“绑架”，采用的的事件驱动的设计模式，采用TabControl控件，当控件初始化后，委托调用application的workbook_open事件，此事件里处理“绑架”，出现的问题为 如果此Tab正常打开，然后用IE浏览器在打开一个Excel文件，然后关闭浏览器，Workbook集合里会有多出一个Ojbect,断点进去查看，此Objcet无正常路径，FullName属性也是Object。
部分代码 ,重写TabControl控件
 
     TabControl部分代码
        #region Win32 API        [DllImport("user32.dll")]
        public static extern int FindWindow(string strclassName, string strWindowName);        [DllImport("user32.dll")]
        static extern int SetParent(int hWndChild, int hWndNewParent);        [DllImport("user32.dll")]
        static extern bool ShowWindow(int hWnd, uint nCmdShow);        [DllImport("user32.dll", EntryPoint = "MoveWindow")]
        static extern bool MoveWindow(
            int Wnd,
            int X,
            int Y,
            int Width,
            int Height,
            bool Repaint
            );        [DllImport("user32.dll", EntryPoint = "SetWindowPos")]
        static extern bool SetWindowPos(
            int hWnd,               // handle to window
            int hWndInsertAfter,    // placement-order handle
            int X,                  // horizontal position
            int Y,                  // vertical position
            int cx,                 // width
            int cy,                 // height
            uint uFlags             // window-positioning options
            );        const int SWP_DRAWFRAME = 0x20;
        const int SWP_NOMOVE = 0x2;
        const int SWP_NOSIZE = 0x1;
        const int SWP_NOZORDER = 0x4;
        const int SWP_HIDEWINDOW = 0x80;
        const int SWP_SHOWWINDOW = 0x40;        const int SW_HIDE = 0;
        const int SW_SHOWNORMAL = 1;
        const int SW_SHOWMINIMIZED = 2;
        const int SW_SHOWMAXIMIZED = 3;
        const int SW_MAXIMIZE = 3;
        const int SW_SHOWNOACTIVATE = 4;
        const int SW_SHOW = 5;
        const int SW_MINIMIZE = 6;
        const int SW_SHOWMINNOACTIVE = 7;
        const int SW_SHOWNA = 8;
        const int SW_RESTORE = 9;        #endregion        #region 自定义事件        public event ApplicationEventHandler ExcelTabControlClosed;        protected virtual void OnExcelTabControlClosed(object sender, ApplicationEventArgs e)
        {
            if (ExcelTabControlClosed != null)
            {
                //ApplicationEventHandler applicationEventHandler = ExcelTabControlClosed as ApplicationEventHandler;
                ExcelTabControlClosed(sender, e);
            }
        }        #endregion        #region 自定义属性
        private int excelApplicationWnd = 0;        public int ExcelApplicationWnd
        {
            get { return excelApplicationWnd; }
            set { excelApplicationWnd = value; }
        }
        public ExcelControl()
        {
            InitializeComponent();
        }        public void FocusExcelApplication()
        {
            ShowWindow(excelApplicationWnd, 5);
        }  
        #endregion        
        #region Excel和页面事件及方法
        //打开Workbook事件
        public void application_WorkbookOpen(object sender, EventArgs e)
        {
            try
            {
                ApplicationEventArgs applicationEventArgs = e as ApplicationEventArgs;                string fileName = applicationEventArgs.Content as string;
                if (fileName.StartsWith("http://")||fileName.Contains(@"Temporary Internet Files"))
                    return;
                FindExcelApplicationWnd();                InitializeTabPage();                ControlExcelApplicationWnd(sender, e);            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.ToString());
            }
        }  ExcelAppliation部分代码
 private Excel.Application application;        public event ApplicationEventHandler WorkbookOpened;        public virtual void OnWorkbookOpened(object sender, ApplicationEventArgs e)
        {
            if (WorkbookOpened != null)
                WorkbookOpened(this, e);
        }        public event ApplicationEventHandler Clear;        public virtual void OnClear(object sender, ApplicationEventArgs e)
        {
            if (Clear != null)
                Clear(this, e);
        }        public Excel.Application Application
        {
            get { return application; }
            set { application = value; }
        }        public ExcelApplication(Excel.Application application)
        {
            this.application = application;
            this.application.WorkbookOpen += new Microsoft.Office.Interop.Excel.AppEvents_WorkbookOpenEventHandler(application_WorkbookOpen);
        }        void application_WorkbookOpen(Microsoft.Office.Interop.Excel.Workbook Wb)
        {
            string name = Wb.FullName;
            if (name.StartsWith("http://")||name.Contains(@"Temporary Internet Files"))
                return;
            ApplicationEventArgs e = new ApplicationEventArgs(name, null);
            OnWorkbookOpened(this, e);
        }        /// <summary>
        /// 恢复Excel工具栏
        /// </summary>
        private void RestoreCommandBar()
        {
            try
            {
                application.DisplayFormulaBar = true;                if (application != null && application.CommandBars != null && application.CommandBars.Count != 0)
                {
                    IEnumerator ie = application.CommandBars.GetEnumerator();
                    while (ie.MoveNext() != false)
                    {
                        Office.CommandBar commandBar = (Office.CommandBar)ie.Current;
                        string name = commandBar.Name;
                        try
                        {
                            commandBar.Enabled = true;
                        }
                        catch (Exception ex)
                        {
                            MessageBox.Show(ex.ToString());
                        }
                    }
                }
            }
            catch
            {
            }
        }
有了解的朋友帮忙解答下，代码比较繁琐，还请见谅