Here is the info. Everything looks fine, doesn't it?

# head /etc/passwd
root:!:0:0:AIX System Account:/:/bin/ksh
daemon:!:1:1:AIX System Account:/etc:
bin:!:2:2:AIX System Account:/bin:
sys:!:3:3:AIX System Account:/usr/sys:
adm:!:4:4:AIX System Account:/var/adm:
nobody:!:-2:-2:AIX System Account:/:
lpd:!:104:-2:AIX System Account:/:
imnadm:!:20:22:AIX System Account:/home/imnadm:/usr/bin/ksh
dev:!:200:1:AIX System Account:/u/dev:/bin/ksh
lowes:!:201:200:lowes:/u/lowes:/bin/ksh

# head /etc/security/passwd
root:
password = pptbHGaco/tFw
lastupdate = 1244092509
flags = NOCHECK
daemon:
password = *
bin:
password = *

# lsuser root
root id=0 pgrp=system groups=system,bin,sys,security,cron,printq,audit,mqm home=/ shell=/bin/ksh gecos=AIX System Account auditclasses=general login=true su=true rlogin=true daemon=true admin=true sugroups=ALL admgroups= tpath=nosak ttys=ALL expires=0 auth1=SYSTEM auth2=NONE umask=22 registry=files SYSTEM=compat logintimes= loginretries=5 pwdwarntime=14 account_locked=false minage=0 maxage=8 maxexpired=4 minalpha=4 minother=1 mindiff=3 maxrepeats=3 minlen=7 histexpire=26 histsize=5 pwdchecks= dictionlist= fsize=-1 cpu=-1 data=262144 stack=65536 core=2097151 rss=65536 nofiles=2000 time_last_login=1205946435 time_last_unsuccessful_login=1244090425 tty_last_login=/dev/tty0 tty_last_unsuccessful_login=/dev/tty0 host_last_login=s1492a host_last_unsuccessful_login=s1492a unsuccessful_login_count=13 roles=