I have a 867MHZ 12" Aluminum PowerBook G4 that will mostly not boot up; to be precise, when I press the power-on button I hear some clicks, which I believe to be the speakers, and I hear the CD-ROM Drive click. Interestingly enough, also, if I hit the "Caps Lock" key, the light indicating that the "Caps Lock" is on is illuminated. This "Caps Lock" light will stay on until I depress the "Caps Lock" key again, or when i hold down the power-on button for five seconds.