C#编写的socket客户端程序，为什么在保存文件的时候程序就好像死循环了

附程序：
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Net;
using System.Net.Sockets;
using System.IO;namespace socket开发指南版客户端
{
    public partial class RemoteFileClient : Form
    {
        protected string hostIp;
        protected int hostPort;
        protected Socket ClientSocket;        public RemoteFileClient()
        {
            InitializeComponent();
        }        public bool GetFile(string fileNameToGet)
        {
            //因为socket只能发送字节，所以有如下的转换
            byte[] senddata = new byte[1024];
            senddata = Encoding.Default.GetBytes(fileNameToGet);
            //发送文件名
            try
            {
                ClientSocket.Send(senddata, senddata.Length, SocketFlags.None);
            }
            catch (Exception ex)
            {
                MessageBox.Show("Error21:" + ex.Message);
                return false;
            }         
                NetworkStream ns = new NetworkStream(ClientSocket);
                byte[] buffer = new byte[1024];
                int readBytes = 0;
                try
                {
                    readBytes = ns.Read(buffer, 0, 1024);
                }
                catch (Exception ex)
                {
                    MessageBox.Show("Error22:" + ex.Message);
                    return false;
                }                string request = Encoding.Default.GetString(buffer,0, readBytes);
                if (request.StartsWith("N")) return false;            //接收文件
            int pos = fileNameToGet.LastIndexOf(@"\") + 1;
            int length = fileNameToGet.Length - pos;
            this.saveFileDialog1.FileName = fileNameToGet.Substring(pos,length);
            if (this.saveFileDialog1.ShowDialog() != DialogResult.OK)
                return false;
            string path = this.saveFileDialog1.FileName;
            MessageBox.Show(path);
            FileStream fs = new FileStream(path, FileMode.OpenOrCreate, FileAccess.Write);
            BinaryWriter bw = new BinaryWriter(fs);
            int count;
            byte[] receivedata = new byte[4096];
            try
            {
                while ((count = ClientSocket.Receive(receivedata ,4096, SocketFlags.None)) != 0)
                {
                   // MessageBox.Show(count.ToString());
                    bw.Write(receivedata, 0, count);
                }
                MessageBox.Show("state:接收成功");
                this.label1.Text = "state:接收成功";
            }
            catch (Exception ex)
            {
                MessageBox.Show("Error23:" + ex.Message);
                return false;
            }
            bw.Close();
            fs.Close();
            return true;
        }        public bool SetUpConnect()
        {
            if (textBox1.Text == "" || textBox2.Text == "" || textBox3.Text == "")
                return false;
            this.hostIp = textBox2.Text.Trim().ToString();
            this.hostPort = int.Parse(textBox3.Text.Trim().ToString());
            try
            {
                IPAddress Ip = IPAddress.Parse(hostIp);
                ClientSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
                ClientSocket.Connect(Ip, hostPort);
            }
            catch (Exception ex)
            {
                MessageBox.Show("ErrorConnect:" + ex.Message);
                return false; ;
            }
            return true;
        }        public void TeardownConnect()
        {
            try
            {
                //ClientSocket.Shutdown();//禁用socket
                ClientSocket.Close();//关闭socket
            }
            catch (Exception ex)
            {
                MessageBox.Show("ErrorDis:" + ex.Message);
            }
        }        private void button3_Click(object sender, EventArgs e)
        {
            if (SetUpConnect())
            {
                this.label2.Text = "State:连接成功";
                bool flag=GetFile(textBox1.Text.Trim().ToString());
                TeardownConnect();
                this.label2.Text = "State:连接断开";
            }
        }        private void button1_Click(object sender, EventArgs e)
        {
            this.openFileDialog1.ShowDialog();
            textBox1.Text = this.openFileDialog1.FileName;
        }
    }
}