My Mac Mini starts but freezes. I get Apple logo but soon the display goes blank and Mac switches off. Can't start in Safe mode or reboot. Can start in single user mode but after all the text appears I'm not able to write anything. Last lines on the display are: BSD root: disk Os3, major 14, minor 12 disk Os3: I/O error. After a while the display runs some texts again and goes blank. Mac also switches off. Does this mean that I have a broken hard disc?