adduser error

[zen]

dear users,
 i have problem with my fresh FreeBSD 6.2 RELEASE
i can not adduser to this machine, the error logs was:

ns1# pw adduser zen -g wheel -d /home/zen -s /bin/csh
pwd_mkdb: corrupted entry
pwd_mkdb: at line #12
pwd_mkdb: /etc/master.passwd: Inappropriate file type or format
pw: user 'zen' disappeared during update
ns1# pw adduser zen -g wheel -d /home/zen -s /bin/csh
pwd_mkdb: corrupted entry
pwd_mkdb: at line #12
pwd_mkdb: /etc/master.passwd: Inappropriate file type or format
pw: user 'zen' disappeared during update

please help regarding this problem

TIA

Zen