I have a few issues with two laptops i own. A macbook black and a Powerbook G4(i think, the one with the silver metal case ". Anyways my Powerbook G4 will not properly boot. I would turn the power button on, then i can hear the fan running - screen remains black - no signs of computer actually booting up. Then; my macbook black seems to lag / freeze for short intervals. The freezing for short intervals started after hearing strange noises with my fan, as if it were stuck or some sort or the other - repeated "clicks". I ruled out the possibilities of it lagging due to overheating (it clearly was not hot). Please list what could be the issues with my laptops. Thanks!