Sounds like you have added NPC's that have models that weren't originally in that zone. You will need to add the relevant lines in the "zonename_chr.txt" (change zonename to the name of the zone in question) in the client folder, or use Akkadius' EOC utility
ref:-
http://wiki.eqemulator.org/p?NPC_Models&frm=Main
and even more helpfully:-
http://eoc.akkadius.com/AC/eoc/min.p...&GenRaceFile=1