Lately as I restart or reboot my IMac G4 running OSX 10.3.9 I get a tone and then the chime at start up. As it starts to "think" I get the fire wire symbol which then goes to a circle w/ a slash as in the universal don't sign. The computer doesn't boot up it stays on the grey screen with the rotating spiral. Any ideas as to why this would happen or how to repair it from happening? I have been able to boot up in safe boot mode though. Thanks for your time and effort.