求大神帮忙看下代码哪有问题

当点击发送时，就卡住不能操作了 是哪的问题啊
下面是完整版代码。        //定义串口对象
        SerialPort myCom = new SerialPort();
        public static int RX = 0;
        public static int TX = 0;
        //定义动态字符串，用来存储接受的数据
        public StringBuilder RecStr = new StringBuilder(4096);        private void FrmRecAndSend_Load(object sender, EventArgs e)
        {
            //初始化comboBox控件
            this.comName.SelectedIndex = 0;
            this.comBaudRate.SelectedIndex = 3;
            this.comByteSize.SelectedIndex = 0;
            this.comParity.SelectedIndex = 0;
            this.comStopBits.SelectedIndex = 0;
        }
        //打开或关闭串口
        private void btnOpen_Click(object sender, EventArgs e)
        {
            if (myCom.IsOpen)
            {
                myCom.Close();
                //状态栏显示串口名称，以及是否为打开状态
                this.statusCom.Text = "STATUS:" + myCom.PortName + "CLOSED!";
                this.btnOpen.Text = "打开串口";
            }
            else
            {
                //初始化串口属性
                this.comboBoxChang();
                myCom.Open();
                //状态栏显示串口名称以及是否为打开状态
                this.statusCom.Text = "STATUS:" + myCom.PortName + "OPENED";
                this.btnOpen.Text = "关闭串口";
                this.timerRec.Enabled = true;
            }
        }        //初始化串口信息
        public void comboBoxChang()
        {
            try
            {
                myCom.PortName = this.comName.SelectedItem.ToString();
                myCom.BaudRate = Convert.ToInt16(this.comBaudRate.SelectedItem.ToString());
                myParity();
                myCom.DataBits = Convert.ToInt16(this.comByteSize.SelectedItem.ToString());
                myStopBits();
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.ToString());
            }
        }
        
        //根据选择确认校验位
        public void myParity()
        {
            if (this.comParity.SelectedIndex == 0)
            {
                myCom.Parity = Parity.None;
            }
            else
            {
                if (this.comParity.SelectedIndex == 1)
                {
                    myCom.Parity = Parity.Odd;
                }
                else
                {
                    myCom.Parity = Parity.Even;
                }
            }
        }        //根据选择确定停止位
        public void myStopBits()
        {
            int caseSwitch = this.comStopBits.SelectedIndex;
            switch (caseSwitch)
            {
                case 1:
                    myCom.StopBits = StopBits.OnePointFive;
                    break;
                case 2:
                    myCom.StopBits = StopBits.Two;
                    break;
                default:
                    myCom.StopBits = StopBits.One;
                    break;
            }
        }        //发送按钮，发送下面的要发送的数据
        private void btnSend_Click(object sender, EventArgs e)
        {
            if (myCom.IsOpen)
            {
                if (this.tBoxSed.Text == "")
                {
                    MessageBox.Show("发送的数据为空");
                }
                try
                {
                    myCom.Write(this.tBoxSed.Text);
                    TX += this.tBoxSed.Text.Trim().ToString().Length;
                    this.tBoxTX.Text = TX.ToString();
                }
                catch (Exception ex)
                {
                    MessageBox.Show("发送数据失败！" + ex);
                }
            }
            else
            {
                MessageBox.Show("请确认串口为打开状态");
            }
        }
        //关闭窗体则关闭串口
        private void FrmRecAndSend_Closing(object sender, CancelEventArgs e)
        {
            myCom.Close();
        }
        
        //去掉发送数组中的空格
        private string delSpace(String putin)
        {
            string putout = "";
            for (int i = 0; i < putin.Length; i++)
            {
                if(putin[i] != ' ')
                {
                    putout += putin[i];
                }            }
            return putout;
        }        //显示包信息
        public string dis_package(char[] recB)
        {
            string tempT = "";
            foreach(char b in recB)
            {
                tempT += b.ToString() + "";
            }
            return tempT;
        }        //自动检测串口是否为打开状态，若为打开状态，自动把接收的数据显示在接收区内
        private void timerRec_Tick(object sender, EventArgs e)
        {
            if (myCom.IsOpen)
            {
                try
                {
                    int numByte = myCom.BytesToRead;
                    if (numByte != 0)
                    {
                        char[] TempByte = new char[2048];
                        int numStr = myCom.Read(TempByte, 0, numByte);
                        RecStr.Append(TempByte);
                        this.tBoxRec.Text = tBoxRec.Text + RecStr.ToString();
                        RX += numStr;
                        this.tBoxRec.Text = RX.ToString();
                        if (this.tBoxRec.Text.Length > 138)
                        {
                            this.tBoxRec.Text = string.Empty;
                        }
                        RecStr.Remove(0, RecStr.Length);
                    }
                }
                catch (Exception ex)
                {
                    MessageBox.Show(ex.ToString());
                }
            }
            else
            {
                this.timerRec.Enabled = false;
            }
        }        //根据时间来自动发送数据
        private void timerAutoSend_Tick(object sender, EventArgs e)
        {
            try
            {
                myCom.Write(this.tBoxSed.Text);
                TX += this.tBoxSed.Text.Trim().ToString().Length;
                this.tBoxTX.Text = TX.ToString();
            }
            catch (Exception ex)
            {
                MessageBox.Show("发送失败!" + ex);
            }
        }
        //检查自动发送的选择按钮是否选中，若选中，则开启自动发送的时间事件
        private void cBoxSendSelf_CheckStateChanged(object sender, EventArgs e)
        {
            if (myCom.IsOpen)
            {
                if (this.tBoxSed.Text == "")
                {
                    MessageBox.Show("发送为空");
                    return;
                }
                else
                {
                    if (this.cBoxSendSelf.Checked == true)
                    {
                        this.timerAutoSend.Interval = Convert.ToInt16(this.tTime.Text.Trim().ToString());
                        this.timerAutoSend.Enabled = true;
                    }
                    else
                    {
                        this.timerAutoSend.Enabled = false;
                    }
                }
            }
            else
            {
                MessageBox.Show("请确定串口为打开状态！");
                this.cBoxSendSelf.Checked = false;
            }
        }        private void btnCountReset_Click(object sender, EventArgs e)
        {
            TX = 0;
            RX = 0;
            this.tBoxTX.Text = TX.ToString();
            this.tBoxRX.Text = RX.ToString();
        }