My 15 inch Tibook (see sig below) is making a strange noise from the HD. Ive narrowed it down to the HD because i can still hear the noise even when the fans have kicked on. Its a high pitched sound of spinning up and down, up and down, up and down and so on. It sounds like its coming from right under the keyboard. If anyone has heard of this or even experienced it in your own machine, please let me know what it is. Thanks a ton for any responses.