Keep the UI on the main thread, webBrowser_DocumentCompleted, waiting on the same line of code

I want to wait for a while on the webBrowser1_DocumentCompleted event. The reason is that the Webbrowser document stream loads well when the next document finishes. I dont want to block the UI when I wait, and I dont want to trigger Document_Completed_Events.

 private void FormTimer()
    {
        webBrowser1.Navigate("http://www.rolex.com/");
        webBrowser1.DocumentCompleted += new WebBrowserDocumentCompletedEventHandler(webBrowser1_DocumentCompleted);
    }
    void webBrowser1_DocumentCompleted(object sender, WebBrowserDocumentCompletedEventArgs e)
    {
        DownloadCount++;
        alarmCounter = 0;
        Task abc = new Task(() =>
        {
            while (alarmCounter < 5)
            {
                Thread.Yield();
            }
        });
        abc.Start();
        Task.WaitAny(abc);
    }

    void timer_Tick(object sender, EventArgs e)
    {
        alarmCounter++;
    }

      

        
        
        
      

    

The problem is that the checkbox stops as it goes to DocumentCompletedEvent.Kindly help me understand the problem and also a good approach for solving these problem situations.

Update: This method works by stripping pending unwanted events and dispatching to DoEvents (). It will also support a UI as well as a timer.

    void webBrowser1_DocumentCompleted(object sender, WebBrowserDocumentCompletedEventArgs e)
    {
        richTextBox1.Text += "\nDocument Started" + documentCount;
        alarmCounter = 0;
        timer.Enabled = true;
        //Do some work
        webBrowser1.DocumentCompleted -= webBrowser1_DocumentCompleted;
        while (alarmCounter < 3)
        {
            Application.DoEvents();            
        }
        webBrowser1.DocumentCompleted += webBrowser1_DocumentCompleted;             
        richTextBox1.Text += "\nDocument Completed." + documentCount;
    }