I have an old IMAC G4 and I'm afraid to power it down because when I do, it doesn't want to come back up. It gets as far as the screen but won't display anything. The only thing that comes up is the spotlight in the corner. If I hold down the option + shift, it will come on after several tries but I have to try to restart it again to get it out of safe boot. I am going to be moving next month and have to power down my computer and I'm afraid if I do, I may never get it back up. Doew anyone know why this is happening?