OSX 10.6 admin account missing
Try restarting and then press Command+S. This will boot the computer in single user mode. After everything loaded, type in ( /sbin/ mount -uw /)first, then (rm /var/db/ .applesetupdone), and finally (shutdown -h now )or (reboot). This erases the previous setup and makes the mac think its brand new. All you would need is to create a new admin account.