is this before the chime or after?, and what comes up for the screen (im an crt apple tech). does it prompt this before the mac logo? durrign grey screen, the brief flash of blue? is there a pin wheel of death?
from what little you tell me it could be ram, an install, corrupted boot setup, or anything really
however in about 10 minutes ill be gone for the day to work, and i cant use this website there. (sorry vgcharts, you still have to much malware for work computers ... my mac at home laughs at them though )
here are a few tips, ask him to hold down when booting, apple(command key on newer keyboards), option, P, R until a second chime sounds.
have him insert if a disk is not already in the disk drive the original install disk that came with the laptop, and hold down option on boot this should take you to a screen that gives you the option to select a disk including your own HD instal, the hardware test included on the original install disk, or to do a fresh install, if the original install is damaged do an archive install and all his files will be fine, as well as apps. his old install will be in a folder on the primary drive. if you suspect a hard ware issue run a HW test looping it is advised on the extended test, it will stop if there is an error note the error and take it to an apple store, or cll them with the code and send it in/ or email them and get a ticket to send it in
many of the other solutions that would work best involve going into single user mode which is a command line prompt, or using a different command line prompt that is also avalible on start up.
I became an apple tech more to work on my own stuff to keep equipment working, rather then send it in. not really to make it a career