That means that you know your calc crashed. This can be caused by taking out the batteries durring running time, happened just randomly. Well nothing to fear just press clear and it should go away but if it stays on that screen you have problems and is best to try some of these methods. Take out all the bateries and press and hold the on button for 30 seconds. Put the batteries back in and it should have reset. Warning you should archive everything incase this happens. To archive go to 2nd mem and hit enter to put a astrick next to the app (meaning archived)