Exceptions to the client when you close the program by pressing ctrl + alt + del

[ServiceBehavior(InstanceContextMode = InstanceContextMode.Single, ConcurrencyMode = ConcurrencyMode.Multiple)]
public class MyService : IMyService
{
    #region Feilds

    private static object syncObj = new object();
    private static Dictionary<IContextChannel, string> _users = new Dictionary<IContextChannel, string>();

    #endregion

    #region Properties

    public IContextChannel CurrentUserChannel { get { return OperationContext.Current.Channel; } }
    public string CurrentUserName
    {
        get
        {
            return OperationContext.Current.ServiceSecurityContext.WindowsIdentity.Name;
        }
    }

    #endregion

    #region IMyService Members

    public void Connect()
    {
        lock (syncObj)
        {
            if (_users.ContainsValue(CurrentUserName))
            {
                _users.Remove(CurrentUserChannel);
            }
            _users.Add(CurrentUserChannel, CurrentUserName);
        }

        CurrentUserChannel.Faulted += new EventHandler(CurrentUserChannel_Faulted);
        CurrentUserChannel.Closing += new EventHandler(CurrentUserChannel_Closing);
    }

    #endregion

    #region Connection Handling

    void CurrentUserChannel_Closing(object sender, EventArgs e)
    {
        HandleChannel(sender as IContextChannel);
    }
    void CurrentUserChannel_Faulted(object sender, EventArgs e)
    {
        HandleChannel(sender as IContextChannel);
    }
    private void HandleChannel(IContextChannel channel)
    {
        if (channel.State == CommunicationState.Closing || channel.State == CommunicationState.Faulted)
        {

            lock (syncObj)
            {
                if (_users.ContainsKey(channel))
                {
                    _users.Remove(channel);
                }
            }
        }
    }

    #endregion

Need the help of professionals. How do I convert an existing source code for the server? Here's the code:
http://www.codeproject.com/script/Articles/ViewDownloads.aspx?aid=25261&zep=WCFWPFApp/ServiceAssembly/ChatService.cs&rzp=/KB/IP/WCFWPFChatRoot//wcfwpfapp.zip