`hi

I am doing a simple synchronous socket programming,in which i employed twothreads one for accepting the client and put the socket object into a collection,other thread will loop through the collection and send message to each client through the socket object.

the problem is

1.i connect to clients to the server and start send messages

2.now i want to connect a new client,while doing this i cant update the collection and add a new client to my hashtable.it raises an exception "collection modified .Enumeration operation may not execute"

how to add a NEW value without having problems in a hashtable.

 private void Listen()
    {
        try
        {
            //lblStatus.Text = "Server Started Listening";
            while (true)
            {
                    Socket ReceiveSock = ServerSock.Accept();
                    //keys.Clear();
                    ConnectedClients = new ListViewItem();
                    ConnectedClients.Text = ReceiveSock.RemoteEndPoint.ToString();
                    ConnectedClients.SubItems.Add("Connected");
                    ConnectedList.Items.Add(ConnectedClients);
                    ClientTable.Add(ReceiveSock.RemoteEndPoint.ToString(), ReceiveSock);
                    //foreach (System.Collections.DictionaryEntry de in ClientTable)
                    //{

                    //    keys.Add(de.Key.ToString());
                    //}
                    //ClientTab.Add(
                    //keys.Add(

            }
            //lblStatus.Text = "Client Connected Successfully.";
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.Message);
        }
    }

    private void btn_receive_Click(object sender, EventArgs e)
    {
        Thread receiveThread = new Thread(new ThreadStart(Receive));
        receiveThread.IsBackground = true;
        receiveThread.Start();
    }
    private void Receive()
    {
        while (true)
        {
            //lblMsg.Text = "";
            byte[] Byt = new byte[2048];
            //ReceiveSock.Receive(Byt);
            lblMsg.Text = Encoding.ASCII.GetString(Byt);
        }
    }

    private void btn_Send_Click(object sender, EventArgs e)
    {
        Thread SendThread = new Thread(new ThreadStart(SendMsg));
        SendThread.IsBackground = true;
        SendThread.Start();
    }

    private void btnlist_Click(object sender, EventArgs e)
    {
        //Thread ListThread = new Thread(new ThreadStart(Configure));
        //ListThread.IsBackground = true;
        //ListThread.Start();
    }
    private void SendMsg()
    {
        while (true)
        {
            try
            {
                foreach (object SockObj in ClientTable.Keys)
                {
                    byte[] Tosend = new byte[2048];
                    Socket s = (Socket)ClientTable[SockObj];
                    Tosend = Encoding.ASCII.GetBytes("FirstValue&" + GenerateRandom.Next(6, 10).ToString());
                    s.Send(Tosend);
                    //ReceiveSock.Send(Tosend);
                    Thread.Sleep(300);
                }

            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
        }

    }