"Monstrous Humanoid" monsters can take "Humanoid" class but shouldn't
pcc loaded "Dungeons & Dragons (v.3.5) System Reference Document" only
creating a new character with all 10, race "Centaur".
it's a "Monstrous Humanoid", and in "Class" tab, under "Monster" type it can advance as "Monstrous Humanoid" class (correctly) and three "Humanoid" classes (it should'nt).
Screenshot of class info panel attached (apparently, the PRERACETYPE requisite isn't correctly checked against RACETYPE or TYPE of the race)
Centaur pcg attached (also a sea hag pcg attached just to confirm that it's not a centaur case, but also other Monstrous Humanoid)
windows seven, java SE runtime environment 1.7.0_51-b13
forget to add (can0t find how to edit):
PCGen v6.07.00-dev autobuild #62 built on 2016-01-18 22:55, +1100