C#网络编程的问题，救命啊，这是怎么回事啊

好吧直接上代码，这是MSDN上套接字使用的服务器端代码，我在窗体上用了个按钮和个Textbox，然后我逐行调试，每次到按下按钮后窗体就现实没有响应了！什么原理啊各位大神！
namespace socket_text
{
    public partial class Server : Form
    {
        static string output = "";
        public Server()
        {
            InitializeComponent();
        }        public void createListener()
        {
            // Create an instance of the TcpListener class.
            TcpListener tcpListener = null;
            IPAddress ipAddress = Dns.GetHostEntry("localhost").AddressList[0];
            try
            {
                // Set the listener on the local IP address
                // and specify the port.
                tcpListener = new TcpListener(ipAddress, 13);
                tcpListener.Start();
                output = "Waiting for a connection...";
            }
            catch (Exception e)
            {
                output = "Error: " + e.ToString();
                MessageBox.Show(output);
            }
            while (true)
            {
                // Always use a Sleep call in a while(true) loop
                // to avoid locking up your CPU.
                textBox1.Text = "等待中";
                Thread.Sleep(10);
                // Create a TCP socket.
                // If you ran this server on the desktop, you could use
                // Socket socket = tcpListener.AcceptSocket()
                // for greater flexibility.
                TcpClient tcpClient = tcpListener.AcceptTcpClient();
                textBox1.Text = "处理中";
                // Read the data stream from the client.
                byte[] bytes = new byte[256];
                NetworkStream stream = tcpClient.GetStream();
                stream.Read(bytes, 0, bytes.Length);
                SocketHelper helper = new SocketHelper();
                helper.processMsg(tcpClient, stream, bytes);
            }
        }        private void button1_Click(object sender, EventArgs e)
        {
            createListener();
        }    }    public class SocketHelper
    {
        TcpClient mscClient;
        string mstrMessage;
        string mstrResponse;
        byte[] bytesSent;
        public void processMsg(TcpClient client, NetworkStream stream, byte[] bytesReceived)
        {
            // Handle the message received and 
            // send a response back to the client.
            mstrMessage = Encoding.ASCII.GetString(bytesReceived, 0, bytesReceived.Length);
            mscClient = client;
            mstrMessage = mstrMessage.Substring(0, 5);
            if (mstrMessage.Equals("Hello"))
            {
                mstrResponse = "Goodbye";
            }
            else
            {
                mstrResponse = "What?";
            }
            bytesSent = Encoding.ASCII.GetBytes(mstrResponse);
            stream.Write(bytesSent, 0, bytesSent.Length);
        }
    }
}网络编程