i have a pb and it was working fine and on occasion would make a beep sound(like that of an alarm clock). then it froze and so i turned it off. i turned it back on the following day and it worked fine but took forever to start. so i decided to turn if off and not have it running all day. well, this time around you see the wheel turning then the apple sign and it goes to blue saying its starting up and nothing. im a bit freaked out because i haven't backed up my work as of recent and it seems to be running but nothing comes up. anyone have any suggestions?