There may be a bug in the RadCheckBox and RadToggleButton control.

[yw]

 When the RadCheckBox or RadToggleButton control is clicked quickly, an exception will be thrown: System.NullReferenceException: "Object reference not set to an instance of an object."

   private void radCheckBox1_ToggleStateChanged(object sender, Telerik.WinControls.UI.StateChangedEventArgs args)
   {
   }

   private void radToggleButton1_ToggleStateChanged(object sender, Telerik.WinControls.UI.StateChangedEventArgs args)
   {
   }