One on my students has a TI-86 that does not work. It can be turned on but can not be turned off. It will shut it self down after a few minutes. All one sees is a the curser. No entry is accepted. No numbers, no letters, no any. She has removed the regular batteries, put them back in, still no improvement. Any suggestion will be appreciated. Thanks. G. Wardall Univ. of Wis.-Green Bay