Friend’s girlfriend locked him out of OS X.

My friend's girlfriend managed to lock him out of OS X. See explanation below. Anyone have an idea on how to set the permissions back. I'm thinking of booting into single user mode and trying a chown command. Ideas? "My girl friend just decided to increase the security on her G5 dp desktop and so she somehow set the permissions for the Owner of the hard drive to "no access". Now when you log on, you get her name and it asks for a password. When you enter the password, which is "9999", it accepts that and them goes to a screen showing just the desktop background with nothing else, ie no dock, no header, no harddrive and the keyboard and mouse are non-responsive."