private void Form1_Load(object sender, EventArgs e)
        {
            toolStripProgressBar1.Maximum = 100;
            toolStripProgressBar1.Value=1;
            while (toolStripProgressBar1.Value <100)
            {
                toolStripProgressBar1.Value = toolStripProgressBar1.Value+1;
                if (toolStripProgressBar1.Value == 99)
                {
                    toolStripProgressBar1.Value = 1;
                } 
            }
        }

public Form1()
        {
            InitializeComponent();
            Control.CheckForIllegalCrossThreadCalls = false;
            
        }

        private void Form1_Load(object sender, EventArgs e)
        {

            Thread t1 = new Thread(new ThreadStart(DoRecycle));
            t1.Start();

        }

        private void DoRecycle()
        {
            pb.Maximum = 100;
            pb.Visible = true;
            pb.Value = 1;
            while (true)
            {
                pb.Value++;
                
                if (pb.Value == 100)
                {
                    pb.Value = 1;
                }
                Thread.Sleep(100);
            }
        }

------解决方案--------------------
像楼主把写在load事件或者按钮click事件直接执行while会导致程序假死，UI主线程一直在执行你的while，跳不出这个循环，根本就没有机会去做其他的事情，想要实现这个效果要再开一个线程去处理进度条（就像16楼），或者用一个System.Windows.Forms.Timer 控件实现，建议楼主去看看多线程、同步、异步