MY MAC (QUADRA 660AV) WON'T START... IT MAKES A SOUND WHEN I START IT, BUT THEN JUST STOPS AFTER ABOUT 3 SECONDS... THE SCREEN STAYS BLACK. IS THERE SOMETHING WRONG WITH MY BATTERY, HARDDISK, LOGICBOARD OR SOMETHING ELSE? PLEASE PLEASE PLEASE HELP ME! THANKS, HARALD, trend@pi.net