C#

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Data;
using System.Data.OleDb;


static class Program
    {
        /// <summary>
        /// The main entry point for the application.
        /// </summary>      
        
        private static bool listening = false;
        private static TcpListener myList;

        [STAThread]
        static void Main()
        {         
            try
            {
                Application.EnableVisualStyles();
                Application.SetCompatibleTextRenderingDefault(false);
                Application.Run(new ConnectionForm());

                IPAddress ipAd = IPAddress.Parse("localhost");
                // use local m/c IP address, and 

                // use the same in the client


                /* Initializes the Listener */
                myList = new TcpListener(ipAd, 8001);
                listening = true;

                /* Start Listeneting at the specified port */
            }
            catch (Exception e)
            {
                Console.WriteLine("Error..... " + e.StackTrace);
            }

            while (listening)
            {
                try
                {
                    Console.WriteLine("The server is running at port 8001...");
                    Console.WriteLine("The local End point is  :" +
                                      myList.LocalEndpoint);
                    Console.WriteLine("Waiting for a connection.....");

                    Socket clientSocket = myList.AcceptSocket();
                    Console.WriteLine("Connection accepted from " + clientSocket.RemoteEndPoint);


                    new Client_sThresds(clientSocket);
                    myList.Start();
                }
                catch (Exception e)
                {
                    Console.WriteLine("Error..... " + e.StackTrace);

                    /* clean up */
                    //clientSocket.Close();
                    myList.Stop();
                }
            }
        }
    }

using System;
using System.IO;
using System.Net;
using System.Net.Sockets;
using System.Text;

         private static TcpListener myList;
/pre>

That is not possible.

Either the usings you posted are incorrect or you have edited your code, not pasted it directly.
<div class="signature">Henry Minute

Do not read medical books! You could die of a misprint. - Mark Twain
Girl: (staring) "Why do you need an icy cucumber?"
"I want to report a fraud. The government is lying to us all."
I wouldn't let CG touch my Abacus!
When you're wrestling a gorilla, you don't stop when you're tired, you stop when the gorilla is.</div>

using System;
using System.Windows.Forms;
using System.Net.Sockets;
using System.Net;

new Client_sThresds(clientSocket);

Marat Beiner wrote:

Just comment that line, and try to run without it.

using System;
using System.Drawing;
using System.Windows.Forms;

public class ColoredButton : Button
{
    public static readonly Color DefaultColorA = Color.Red;
    public static readonly Color DefaultColorB = Color.Green;
    public const int DefaultInterval = 1000;

    public event EventHandler Tick;

    private Color colorA;
    private Color colorB;
    private Timer timer;

    public ColoredButton()
    {
        colorA = DefaultColorA;
        colorB = DefaultColorB;
        BackColor = colorA;
        timer = new Timer();
        timer.Interval = DefaultInterval;
        timer.Tick += TimerTick;
    }

    public Color ColorA
    {
        get { return colorA; }
        set { colorA = value; }
    }
    public Color ColorB
    {
        get { return colorB; }
        set { colorB = value; }
    }
    public int Interval
    {
        get
        {
            if (timer != null)
                return timer.Interval;
            else
                return DefaultInterval;
        }
        set
        {
            if (timer != null)
                timer.Interval = value;
        }
    }

    protected override void Dispose(bool disposing)
    {
        if (disposing && timer != null)
        {
            timer.Dispose();
            timer = null;
        }
        base.Dispose(disposing);
    }
    protected virtual void OnTick(EventArgs e)
    {
        EventHandler eh = Tick;
        if (eh != null)
            eh(this, e);
    }
    public void Start()
    {
        if (timer != null)
            timer.Start();
    }
    public void Stop()
    {
        if (timer != null)
            timer.Stop();
    }
    private void TimerTick(object sender, EventArgs e)
    {
        if (BackColor == colorA)
            BackColor = colorB;
        else
            BackColor = colorA;
        OnTick(EventArgs.Empty);
    }
}

using System;
using System.Collections.Generic;
using System.Text;
using System.Drawing;
using System.Windows.Forms;

namespace ClassLibrary1
{
public class ColoredButton 
    {
        public static readonly Color DefaultColorA = Color.Red;
        public static readonly Color DefaultColorB = Color.Green;
        public const int DefaultInterval = 1000;

        public event EventHandler Tick;

        private Color colorA;
        private Color colorB;
        private Timer timer;

        public ColoredButton()
        {
            colorA = DefaultColorA;
            colorB = DefaultColorB;
            BackColor = colorA;
            timer = new Timer();
            timer.Interval = DefaultInterval;
            timer.Tick += TimerTick;
        }

        public Color ColorA
        {
            get { return colorA; }
            set { colorA = value; }
        }
        public Color ColorB
        {
            get { return colorB; }
            set { colorB = value; }
        }
        public int Interval
        {
            get
            {
                if (timer != null)
                    return timer.Interval;
                else
                    return DefaultInterval;
            }
            set
            {
                if (timer != null)
                    timer.Interval = value;
            }
        }

        protected override void Dispose(bool disposing)
        {
            if (disposing && timer != null)
            {
                timer.Dispose();
                timer = null;
            }
            base.Dispose(disposing);
        }
        protected virtual void OnTick(EventArgs e)
        {
            EventHandler eh = Tick;
            if (eh != null)
                eh(this, e);
        }
        public void Start()
        {
            if (timer != null)
                timer.Start();
        }
        public void Stop()
        {
            if (timer != null)
                timer.Stop();
        }
        private void TimerTick(object sender, EventArgs e)
        {
            if (BackColor == colorA)
                BackColor = colorB;
            else
                BackColor = colorA;
            OnTick(EventArgs.Empty);
        }
    }
}