System.Windows.Forms.Timer timer = new System.Windows.Forms.Timer();
System.Windows.Forms.Form form = new System.Windows.Forms.Form();
form.Load += delegate (object s, EventArgs e) {
timer.Interval = 10000; //время ожидания
timer.Tick += new EventHandler(delegate (object _s, EventArgs _e){
timer.Stop();
//здесь обработка полей формы
form.Close();
});
timer.Start();
};
form.ShowDialog();