Mac OS X recovery

Special key combinations

Any of the following key combinations can be invoked when the machine is turned on, immediately after the startup chime has sounded:

cmd-v	verbose
cmd-s	single-user mode
shift	safe mode (and disable all login items)
opt	startup manager
cmd-opt-o-f	open firmware
cmd-.	open/close CD tray
c	boot from CD/DVD
d	boot from diagnostic volume of install CD/DVD
t	firewire target mode
cmd-opt-shift-del	bypass primary startup volume
cmd-opt-p-r	zap PRAM
mouse button	eject all removable media

Disk repair

Try to boot from the install CD. Select Disk Utilities from the menu bar. Select repair permissions and repair volume.

If cannot manage to boot from the install CD, you may be able to boot from an external volume using the startup manager. The external volume could be another Mac in fireware target mode.

Another possibility is a manual repair. Boot into open firmware and type

reset-nvram
reset-all

Then boot into single user mode and type

diskutil info /
/sbin/fsck -fy
reboot