System.ObjectDisposedException: 无法访问已释放的对象。

我用C#仿照别人的写一个控件,其中用到了WebBrowser, 编译后放到HTML中,结果确出现以下错误
有关调用实时(JIT)调试而不是此对话框的详细信息，
请参见此消息的结尾。************** 异常文本 **************
System.ObjectDisposedException: 无法访问已释放的对象。
对象名:“WebBrowser”。
   在 System.Windows.Forms.WebBrowser.get_AxIWebBrowser2()
   在 System.Windows.Forms.WebBrowser.PerformNavigate2(Object& URL, Object& flags, Object& targetFrameName, Object& postData, Object& headers)
   在 System.Windows.Forms.WebBrowser.PerformNavigateHelper(String urlString, Boolean newWindow, String targetFrameName, Byte[] postData, String headers)
   在 System.Windows.Forms.WebBrowser.Navigate(String urlString)
   在 CSharpActiveX.Hello.btnGo_Click(Object sender, EventArgs e) 位置 D:\VC++\CSharpActiveX\CSharpActiveX\Hello.cs:行号 110
   在 System.Windows.Forms.Control.OnClick(EventArgs e)
   在 System.Windows.Forms.Button.OnClick(EventArgs e)
   在 System.Windows.Forms.Button.OnMouseUp(MouseEventArgs mevent)
   在 System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
   在 System.Windows.Forms.Control.WndProc(Message& m)
   在 System.Windows.Forms.ButtonBase.WndProc(Message& m)
   在 System.Windows.Forms.Button.WndProc(Message& m)
   在 System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
   在 System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
   在 System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)************** JIT 调试 **************
要启用实时(JIT)调试，
该应用程序或计算机的 .config 文件(machine.config)的 system.windows.forms 节中必须设置
jitDebugging 值。
编译应用程序时还必须启用
调试。例如: <configuration>
    <system.windows.forms jitDebugging="true" />
</configuration>启用 JIT 调试后，任何无法处理的异常
都将被发送到在此计算机上注册的 JIT 调试器，
而不是由此对话框处理。HTML文件代码是
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<title>ActiveX测试</title>
</head>
<object id="csharpActiveX" classid="clsid:4A44CF4E-F859-4328-AA22-3E9D7AFFF1AB"></object>
<input type="button" onclick="alert(csharpActiveX.SayHello());" value="显示当前时间" />
<body>
</body>
</html>C#的原代码:
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Drawing;
using System.Data;
using System.Text;
using System.Windows.Forms;
using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;
using System.Security; namespace CSharpActiveX
{
    [Guid("4A44CF4E-F859-4328-AA22-3E9D7AFFF1AB")]
    public partial class Hello : UserControl, IObjectSafety
    {
        public Hello()
        {
            InitializeComponent();
        }        #region　IObjectSafety　成员
        private const string _IID_IDispatch = "{00020400-0000-0000-C000-000000000046}";
        private const string _IID_IDispatchEx = "{a6ef9860-c720-11d0-9337-00a0c90dcaa9}";
        private const string _IID_IPersistStorage = "{0000010A-0000-0000-C000-000000000046}";
        private const string _IID_IPersistStream = "{00000109-0000-0000-C000-000000000046}";
        private const string _IID_IPersistPropertyBag = "{37D84F60-42CB-11CE-8135-00AA004BB851}";
        private const int INTERFACESAFE_FOR_UNTRUSTED_CALLER = 0x00000001;
        private const int INTERFACESAFE_FOR_UNTRUSTED_DATA = 0x00000002;
        private const int S_OK = 0;
        private const int E_FAIL = unchecked((int)0x80004005);
        private const int E_NOINTERFACE = unchecked((int)0x80004002);
        private bool _fSafeForScripting = true;
        private bool _fSafeForInitializing = true;
        public int GetInterfaceSafetyOptions(ref　Guid riid, ref　int pdwSupportedOptions, ref　int pdwEnabledOptions)
        {
            int Rslt = E_FAIL;
            string strGUID = riid.ToString("B");
            pdwSupportedOptions = INTERFACESAFE_FOR_UNTRUSTED_CALLER | INTERFACESAFE_FOR_UNTRUSTED_DATA;
            switch (strGUID)
            {
                case _IID_IDispatch:
                case _IID_IDispatchEx:
                    Rslt = S_OK;
                    pdwEnabledOptions = 0;
                    if (_fSafeForScripting == true)
                        pdwEnabledOptions = INTERFACESAFE_FOR_UNTRUSTED_CALLER;
                    break;
                case _IID_IPersistStorage:
                case _IID_IPersistStream:
                case _IID_IPersistPropertyBag:
                    Rslt = S_OK;
                    pdwEnabledOptions = 0;
                    if (_fSafeForInitializing == true)
                        pdwEnabledOptions = INTERFACESAFE_FOR_UNTRUSTED_DATA;
                    break;
                default:
                    Rslt = E_NOINTERFACE;
                    break;
            }
            return Rslt;
        }
        public int SetInterfaceSafetyOptions(ref　Guid riid, int dwOptionSetMask, int dwEnabledOptions)
        {
            int Rslt = E_FAIL;
            string strGUID = riid.ToString("B");
            switch (strGUID)
            {
                case _IID_IDispatch:
                case _IID_IDispatchEx:
                    if (((dwEnabledOptions & dwOptionSetMask) == INTERFACESAFE_FOR_UNTRUSTED_CALLER) && (_fSafeForScripting == true))
                        Rslt = S_OK;
                    break;
                case _IID_IPersistStorage:
                case _IID_IPersistStream:
                case _IID_IPersistPropertyBag:
                    if (((dwEnabledOptions & dwOptionSetMask) == INTERFACESAFE_FOR_UNTRUSTED_DATA) && (_fSafeForInitializing == true))
                        Rslt = S_OK;
                    break;
                default:
                    Rslt = E_NOINTERFACE;
                    break;
            }
            return Rslt;
        }
        #endregion        private void button1_Click(object sender, EventArgs e)
        {
            SetTime(DateTime.Now.ToLongTimeString());
        }        public void SetTime(string timeStr)
        {
            this.label2.Text = timeStr;
        }        public void SayHello()
        {
            SetTime("出错了");
        }        private void button2_Click(object sender, EventArgs e)
        {
            this.label2.BackColor = Color.Red;
        }        private void btnGo_Click(object sender, EventArgs e)
        {
            this.Browser.Navigate(txtAddr.Text);
        }        private void btnPreview_Click(object sender, EventArgs e)
        {
            IOleCommandTarget pCmdTarg = Browser.ActiveXInstance as IOleCommandTarget;
            Guid CGID_MSHTML = GlobalConst.CGID_MSHTML;            string vTemplatePath = txtTemplateAddr.Text;
            Object[] o = new object[1] { vTemplatePath };            pCmdTarg.Exec(ref CGID_MSHTML,
                GlobalConst.IDM_PRINTPREVIEW,
                (uint)OLECMDEXECOPT.OLECMDEXECOPT_PROMPTUSER,
                o,
                null);
        }        private void btnPrint_Click(object sender, EventArgs e)
        {
            IOleCommandTarget pCmdTarg = Browser.ActiveXInstance as IOleCommandTarget;
            Guid CGID_MSHTML = GlobalConst.CGID_MSHTML;            string vTemplatePath = txtTemplateAddr.Text;
            Object[] o = new object[1] { vTemplatePath };            pCmdTarg.Exec(ref CGID_MSHTML,
                GlobalConst.IDM_PRINT,
                (uint)OLECMDEXECOPT.OLECMDEXECOPT_PROMPTUSER,
                o,
                null); 
        }
    }
}接口IObjectSafety.cs:
using System;
using System.Collections.Generic;
using System.Text;
using System.Runtime.InteropServices;  namespace CSharpActiveX
{
    [ComImport, GuidAttribute("CB5BDC81-93C1-11CF-8F20-00805F2CD064")]
    [InterfaceTypeAttribute(ComInterfaceType.InterfaceIsIUnknown)]  
    public interface IObjectSafety
    {
        [PreserveSig]
        int GetInterfaceSafetyOptions(ref Guid riid, [MarshalAs(UnmanagedType.U4)] ref int pdwSupportedOptions, [MarshalAs(UnmanagedType.U4)] ref int pdwEnabledOptions); 
        [PreserveSig()] 
        int SetInterfaceSafetyOptions(ref Guid riid, [MarshalAs(UnmanagedType.U4)] int dwOptionSetMask, [MarshalAs(UnmanagedType.U4)] int dwEnabledOptions); 
    }  
}接口IOleCommandTarget.cs:
using System;
using System.Collections.Generic;
using System.Text;
using System.Runtime.InteropServices;
using System.Runtime.InteropServices.ComTypes;namespace CSharpActiveX
{
    [ComImport(), Guid("B722BCCB-4E68-101B-A2BC-00AA00404770"),
    InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]    public interface IOleCommandTarget
    {
        [PreserveSig()]
        int QueryStatus([In, MarshalAs(UnmanagedType.Struct)] ref Guid
           pguidCmdGroup, [MarshalAs(UnmanagedType.U4)] int cCmds,
           [In, Out] IntPtr prgCmds, [In, Out] IntPtr pCmdText);
        [PreserveSig()]
        int Exec(ref Guid pguidCmdGroup, uint nCmdID, uint nCmdExecOpt,
            [In, MarshalAs(UnmanagedType.LPArray)] object[] pvaIn,
            [In, Out, MarshalAs(UnmanagedType.LPArray)] object[] pvaOut);    }    public enum OLECMDEXECOPT
    {
        OLECMDEXECOPT_DODEFAULT,
        OLECMDEXECOPT_PROMPTUSER,
        OLECMDEXECOPT_DONTPROMPTUSER,
        OLECMDEXECOPT_SHOWHELP
    }
    public static class GlobalConst
    {
        public const int MSOCMDEXECOPT_DONTPROMPTUSER = 2;
        public const int IDM_PRINT = 0x1b;
        public const int IDM_PRINTPREVIEW = 0x7d3;
        public static readonly Guid CGID_MSHTML = new Guid("DE4BA900-59CA-11CF-9592-444553540000");
        public static readonly Guid IID_OleCommandTarget = new Guid("B722BCCB-4E68-101B-A2BC-00AA00404770");
    }}生成后
再部署安装Setup后打开HTML页,click me和button2均无问题,
在Document address中输入:http://www.sohu.com 然后点击Go就出现上面的错误.
也就是说程序在
        private void btnGo_Click(object sender, EventArgs e)
        {
            this.Browser.Navigate(txtAddr.Text);
        }
出错,不知怎样解决.