FreeBSD 6.x, NIS, local root password, and nsswitch.conf

[freebsd-stable-archive at cloud9.net]

I have a new system that has FreeBSD 6.1 on it to replace a system with 
FreeBSD 4.11 being put out of service.

I want to keep to using local root passwords only, but export other users' 
logins over NIS.  It acts presently as an NIS slave server.

The NIS master server was upgraded a few months ago to FreeBSD 6.0 and 
then 6.1.

All other machines are running FreeBSD 4.11.

A weird thing started to happen with the new machine.  Only on this new 
machine, the local root password doesn't work and only the root
password of the NIS master server will work to attain root.  Perhaps 
something needs to be changed somewhere to make the local root
password work again?

Here's the /etc/nsswitch.conf from the master server:
group: compat
group_compat: nis
hosts: files dns
networks: files
passwd: compat
passwd_compat: nis
shells: files

Here's the /etc/nsswitch.conf from the slave server:
group: compat
group_compat: nis
hosts: files dns
networks: files
passwd: compat
passwd_compat: nis
shells: files

They both appear to be set to defaults.

I tried changing group and passwd to include 'files', I also tried 
changing group_compat and passwd_compat to include 'files', but no
positive change.

I couldn't find nsswitch.conf on any of the FreeBSD 4.11 servers.  They 
are served by NIS as clients and all of their local root passwords
work fine.

Where should I look next?

Thanks!


--
Mark P. Hennessy