I started up my G5 today and after the bong it just went to a blank screen with a blinking planet earth icon. after a few seconds the icon stopped blinking and changed to a folder icon. within a minute or so the fans started revving up... what's this all about? i took a chance/guess and powered down and powered back up and zapped the PRAM. this did the trick (otherwise i wouldn't be typing this right now). what happened?