HI! i have a 17" g4 pb. it started acting up this evening. tried to reinstall avid xpress pro cd. installation took FOREVER. machine became very slow and stalled. ran disk doctor and that took forever. had to constantly force quit applications and reboot. after rebooting my computer was stuck on grey screen with apple and black pinwheel. stayed that way for over 30mn. i zapped pram and it's still stuck on grey screen with apple. but no black pinwheel. i dont know what to do! i dont want to loose all my info! was not doing this ever before! someone please HELP ME!! THANX!!