[Samba] all machine password changes fail

[Mark]

None of the Win 2000 workstations on my Samba 3.02 network is able to change
its password.  Every machine's event log contains error messages every 30
days like this:

Changing machine account password for account P2450-2$ failed with the
following error:
The stub received bad data.

For the machines that are restarted every day, the error message only
appears once or twice evey 30 days.  For machines that are always on, the
error appears many times before the machine gives up and waits another 30
days.  Everything else works fine, so it isn't causing any great problems,
but I suppose it isn't the best security either, if the machine passwords
are forever stuck.

The Samba server is a PDC.  The password backend is smbpasswd.

Mark