Samba setup essentially as a PDC with encrypted passwords, when enabling "unix
password sync", unprivileged users cannot change their password using the
"smbpasswd" command, the following error is produced:

[user@server /]$ smbpasswd
Old SMB password:
New SMB password:
Retype new SMB password:
machine 127.0.0.1 rejected the password change: Error was : RAP86: The specified
password is invalid.
Failed to change password for user

If you turn off "unix password sync", then non-root users can then change their
own passwords.  I also note that trying to change your password from a Windows
machine produces the same failure to change password when unix password sync is
enabled.

I have tested this on a Fedora Linux Core 1 machine with Samba versions 2.2.8a
and 3.0.2, and with 2.2.8a on a Red Hat Linux 7.3 machine and it produces
exactly the same results.  I double checked my smb.conf configuration with John
Terpstra via the Samba mailing list and he commented that he can reproduce
exactly the same problem himself and suggested I make this bug report.

Thanks for your time. :)