怎么用两个线程，同时让两个label 漂移起来

Question

public void ChinaHappyBirthday()//中文label
        {
            if (InvokeRequired)
            {
                Invoke(new MethodInvoker(ChinaHappyBirthday));
            }
            else
            {
                while(true)
                {                       
                    if (label1.Left > this.Width)
                    {
                        label1.Left = 0;
                    }
                    label1.Left += Rand();
                    label1.Refresh();
                    Thread.Sleep(10);
                }
            }
        }
        public void EnglishHappyBirthday()//英文label
        {
            if (InvokeRequired)
            {
                Invoke(new MethodInvoker(EnglishHappyBirthday));
            }
            else
            {
                while(true)
                {                
                    if (label2.Left >=this.Width)
                    {                        
                        label2.Left = 0;
                    }
                    label2.Left += Rand();
                    label2.Refresh();
                    Thread.Sleep(10);
                }   
            }
        }
＝＝＝＝＝＝＝＝＝下面我用了两个线程，使上面的两个label能同时漂移
　　　　private Thread pri1;
        private Thread pri2;
        private void button1_Click(object sender, EventArgs e)
        {
            pri1 = new Thread(new ThreadStart(ChinaHappyBirthday));
            pri2 = new Thread(new ThreadStart(EnglishHappyBirthday));
            pri3 = new Thread(new ThreadStart(txt));
            pri1.Start();
            pri2.Start();
        }此代码的目的是为了让label能横向的循环漂移，我定义了两个label，分别是中文的和英文的，我要用两个线程同时让它漂移起来，但是结果是只有pri1　这个线程不停的移动，pri2这个线程不动，怎么办？

Answer 1

public void ChinaHappyBirthday()
        {
            if (InvokeRequired)
            {
                Invoke(new MethodInvoker(ChinaHappyBirthday));
            }
            else
            {
                while(true)
                {                       
                    if (label1.Left > this.Width)
                    {
                        label1.Left = 0;
                    }
                    label1.Left += Rand();
                    label1.Refresh();
                    //
                    if (label2.Left >= this.Width)
                    {
                        label2.Left = 0;
                    }
                    label2.Left += Rand();
                    label2.Refresh();
                    //
                    if (label3.Top >= 600)
                    {
                        label3.Top = 0;
                    }
                    label3.Top += Rand();
                    label3.Refresh();
                    Thread.Sleep(10);
                }
            }
        }
　　　　private Thread pri1;
        private void button1_Click(object sender, EventArgs e)
        {
            pri1 = new Thread(new ThreadStart(ChinaHappyBirthday));
            pri1.Start();
        }
=============
用一个线程是实现了，可是为什么，label　转了几圈以后，窗口图像就乱了呢，一片白色，里面的内容显示不出来，好像死掉似的，求教

Answer 2

private void button2_Click(object sender, EventArgs e)
        {
            pri1.Suspend();
        }而且用按钮，暂时停线程运行，它停不下来