I have PB G4 1,3Ghz 17 .When I press the power button it starts,makes normal sound,screen flashes,then the small white flashing square with the Globe,(American continent,blue colour) appears on the screen ,then after 20-30 secs. little typical square (as if the s/w and the hdd are not present)The dvd drive reacts to the CD,there is a spinning sound of the HDD,but no boot.Please advise what that flashing globe tryes to say?Regards