各位大侠，急急急啊！C#串口通信接发程序

在没有发送的情况下，按下接收数据按钮时，程序窗口就卡住了，如果我改成if（data==null）或者if（data==“”）之类的表达都没有用啊，还是会卡住。但是如果我button1里面的程序剪到serialPort1_DataReceived里面就不会卡，可是这样好像接收不到数据，菜鸟不懂啊，请各位大侠求助。谢谢了。
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.IO.Ports;namespace 串口接收端
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }        private void Form1_Load(object sender, EventArgs e)
        {
            this.AcceptButton = button2;
            serialPort1.PortName = "COM8";
            serialPort1.BaudRate = 9600;
            serialPort1.DataBits = 8;
            serialPort1.StopBits = StopBits.One;
            serialPort1.Parity = Parity.None;
            serialPort1.DataReceived +=new SerialDataReceivedEventHandler(serialPort1_DataReceived);
            serialPort1.Open();
        }        private void button1_Click(object sender, EventArgs e)
        {//接收数据                      byte[] data = Convert.FromBase64String(serialPort1.ReadLine());      
                            try
                {
                    tbxInt.Text += Encoding.Unicode.GetString(data);
                    serialPort1.Close();                }
                catch (Exception)
                {
                    MessageBox.Show("读取串口数据时发生错误");
                }
            
            
        }
        
        private void serialPort1_DataReceived(object sender, SerialDataReceivedEventArgs e)
        {        }        private void button2_Click(object sender, EventArgs e)
        {//数据发送
           
            if (tbxInt2.Text == "")
            {
                MessageBox.Show("请输入要发送的数据");
            }
            else
            {                try
                {
                    byte[] data = Encoding.Unicode.GetBytes(tbxInt2.Text);
                    string str = Convert.ToBase64String(data);
                    serialPort1.WriteLine(str);
                    
                }
                catch (Exception)
                {
                    MessageBox.Show("发送数据时发生错误");
                    return;
                }                tbxInt2.Text = "";
            }
            
        }
    }
}