if the hard drive is able to be booted at all, then this indicates its a software glitch of some sort...but i suspect there's more to the problem (ie user error or "fiddling") that isn't being mentioned...hard drives can and do wear out/have problems/ get glitches...but from the scant information here, with lights working and power going to the 'board and the hard drive spinning up...i would humbly suggest its a software prob..perhaps if he re-installs an earlier op sys, and full resources, this might fix it? bear in mind the op system and resources should be the same version ie 1.5op sys +1.5resources 2.0op sys+2.0resources etc etc.

peace, out