Перестает обновляться страница

У меня есть таймер и в таймере перезагрузка страницы и со временем она перестает перезагружаться. Почему?

System.setProperty("webdriver.chrome.driver", "C:\\Users\\" + System.getProperty("user.name") + "\\chromedriver.exe");
WebDriver driver = new ChromeDriver();
driver.manage().window().maximize();
driver.manage().deleteAllCookies();
driver.manage().timeouts().pageLoadTimeout(40, TimeUnit.SECONDS);
driver.manage().timeouts().implicitlyWait(30, TimeUnit.SECONDS);
driver.get("https://www.instagram.com/accounts/login/?hl=ru");
final ScheduledExecutorService ses = Executors.newSingleThreadScheduledExecutor();
ses.scheduleWithFixedDelay(new Runnable() {
  @Override
  public void run() {
    String Nachtext;
    driver.navigate().refresh();
    Random ran = new Random();
    unit = ran.nextInt(14) + 1;
    try {
      Thread.sleep(unit * 1000);
    } catch (InterruptedException e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
    }
    driver.navigate().refresh();
  }
}, 0, 2, TimeUnit.SECONDS);

Все, что в консоли:

Starting ChromeDriver 76.0.3809.126 (d80a294506b4c9d18015e755cee48f953ddc3f2f-refs/branch-heads/3809@{#1024}) on port 22837
Only local connections are allowed.
Please protect ports used by ChromeDriver and related test frameworks to prevent access by malicious code.
[1571149971.304][WARNING]: This version of ChromeDriver has not been tested with Chrome version 77.
окт 15, 2019 5:32:51 PM org.openqa.selenium.remote.ProtocolHandshake createSession
INFO: Detected dialect: W3C
[1571151035.059][SEVERE]: Timed out receiving message from renderer: 1.030
[1571151035.064][SEVERE]: Timed out receiving message from renderer: -0.005