Sounds like someone edited the password file directly with vi, instead of
using the vipw program, and now the shadow password files is out of sync, or
someone
had vipw open and didn't exit properly, leaving a temp file.
In /etc you should have the following:
pwd.db
spwd.db
passwd
master.passwd
All four should have the same date and time stamp. The 2 db files should be
exactly the same size
If you have any other files like passwd.XXXX then delete them, these are
temp
files.
/usr/sbin/pwd_mkdb -p /etc/master.passwd
"had vipw open and didn't exit properly,"
ps -aux
and drilling down on logs to see who is running vipw.