TCP/IP sending and receiving threads

It's my first stab at TCP/IP and honestly I'm just starting out on C# also, so any comments on the design, method, etc are more than welcome.

Basically I wanted to create a listening thread and someday a sending thread, that can handle listen/send heartbeat message and also other messages.

Once it retrieve the message, it will update some value back into the main execution program.

public virtual void StartReceivingThread()
{
    Thread thrReceive = new Thread(Receive);
    try
    {
        if (!bIsActive && Connect())
        {
            //NOTE: exception thrown by a thread can only be captured by that thread itself
            //start a listen thread
            //wait until heartbeat message is accepted

            thrReceive.Name = "thr" + serviceType.Name;
            thrReceive.Start();
            bIsActive = true;

            //wait to get the heartbeat message
            for (int i = 0; i < maxRetry; i++)
            {
                Thread.Sleep(maxTimeOutValue);
                if (bIsReceivingHeartbeat)
                    break;
            }
            //if nothing happens close the connection and try again
            if (!bIsReceivingHeartbeat)
            {
                bIsActive = false;
                CleanUp();
                logger.Info("Closing  receiver thread - " + thrReceive.Name);
            }
            else
            {
                logger.Info("Starting  receiver thread - " + thrReceive.Name);
            }
        }


    }
    catch(Exception ex)
    {
        logger.Error(ex);
    }
    //finally
    //{
    //    logger.Info("Exiting  receiver thread - " + thrReceive.Name);
    //}
}

public void CleanUp()
{
    if (client != null)
    {
        client.Close();
    }
}

public virtual void Receive()
{
    string eventMessage = string.Empty;
    int bytesRcvd = 0;
    int totalBytesRcvd = 0;
    byte[] byteBuffer = new byte[maxBufferSize];
    NetworkStream listenStream;
    try
    {
        if (client.Connected)
        {
            listenStream = client.GetStream();    
        }
        else
        {
            return;
        }

        while (true)
        {                
            //message that is slot in from the object will get sent here.
            if (!string.IsNullOrEmpty(MessageToSend))
            {
                Send(MessageToSend);
                MessageToSend = string.Empty;
            }

            // must convert it back and look for the delimiter, cannot wait for the three heartbeat to pass
            string leftoverMsg = string.Empty;

            bytesRcvd = listenStream.Read(byteBuffer, totalBytesRcvd, maxBufferSize - totalBytesRcvd);
            totalBytesRcvd += bytesRcvd;

            //if more than heart beat size, can process to see if it's a heartbeat and proceed to send
            if (totalBytesRcvd > msgHeartbeatSize)
            {
                eventMessage = Encoding.ASCII.GetString(byteBuffer, 0, totalBytesRcvd);
                ProcessMessage(eventMessage, ref leftoverMsg, ref totalBytesRcvd, ref byteBuffer);
            }
        }
    }
    catch (ThreadAbortException thEx)
    {
        //do nothing as main thread has aborted and waiting to close
        logger.Info(Thread.CurrentThread.Name + " is stopped. ");
    }
    catch (Exception exce)
    {
        bIsActive = false;
        logger.Error(exce);
        CleanUp();
    }
    finally
    {
        logger.Info(String.Format("Thread {0} Exiting. ", Thread.CurrentThread.Name));
    }
}

public void Send(string msg)
{
    StringBuilder sb = new StringBuilder();
    sb.Append(Char.STX);
    sb.Append(msg);
    sb.Append(Char.ETX);

    try
    {
        string message = sb.ToString();
        byte[] byteBuffer = Encoding.ASCII.GetBytes(message);

        //use a different stream to prevent blocking?
        NetworkStream sendNetStream = client.GetStream();
        sendNetStream.Write(byteBuffer, 0, byteBuffer.Length);
        sendNetStream.Flush(); //clear buffer straight without waiting for the write buffer to fill up.

        //simplify the heart beat message for logging
        if (simpleHeartbeatMsg.ToLower().Contains("on") 
            && message.Contains("fnxheartbeatack"))
        {
            message = "heartbeat message.";
        }
        logger.Info("Sending to   - xml: " + Char.GetNonFormattedString(message));

    }
    catch (Exception ex)
    {
        bIsActive = false;
        CleanUp();
        sb = null;
        throw ex;
    }
}