samba - Oct 2005 - 3.0.5 PDC - Critical Netlogon Failure for Domain Members

The Samba service (3.0.5) running on our Mac OS X Server (10.3.8) is the
primary domain controller (PDC) for around 25 Windows XP desktops and two
Windows 2000 Servers. These domain members are reporting a slew of errors in
their System logs. The following message appears every 4 hours:

Source: NETLOGON 
Type: Error 
Event ID: 3224 

"Changing the machine account password for account JASONHEISER$ failed with
the following error: A device attached to the system is not functioning."

This is a non-fatal error. However, this error eventually culminates (I
think) into a more critical problem:

Source: Netlogon 
Type: Error 
Event ID: 3210 

"Failed to authenticate with \\MRWINT, a Windows NT or Windows 2000 domain
controller for domain CPI."

This is a fatal error. The computer can no longer authenticate itself to
anything on the domain. The computer must then reboot.

It takes a while for this authentication failure to occur. Most of the XP
workstations are shut down each night and never experience it. The Windows
2000 Servers, which are running 24/7, succumb to this error every 1-4 weeks.
Since they handle print services and our ERP software, this failure is a
showstopper.

It's only my hunch that the benign 3224 error is a symptom leading to the
fatal 3210 error. I could be wrong. It could be a red herring.

I can usually Google my way through most problems, but I'm stumped by this
one. Any guru-level Samba wonks out there who can lead the way?