Vista - Vista domain PC auth failures 529 and 680 on w2k3 file server every2 min

We have 6 Vista (ultimate, business, enterprise) on our 2k3 domain.
Since joining the PCs to our domain the file server has logged two audit
failures every 2 minutes for each machine. The failures are below.
Disabling the local user account created during the vista install stops
the audit failures. I temporarily disabled indexing and it had no
affect. Has anyone seen a similar issue?


Event Type: Failure Audit
Event Source: Security
Event Category: Logon/Logoff
Event ID: 529
Date: 1/16/2007
Time: 3:26:29 PM
User: NT AUTHORITY\SYSTEM
Computer: <file server name>
Description:
Logon Failure:
Reason: Unknown user name or bad password
User Name: <local username>
Domain: <local vista pc name>
Logon Type: 3
Logon Process: NtLmSsp
Authentication Package: NTLM
Workstation Name: <local vista pc name>
Caller User Name: -
Caller Domain: -
Caller Logon ID: -
Caller Process ID: -
Transited Services: -
Source Network Address: <local vista pc ip>
Source Port: 0


For more information, see Help and Support Center at
http://go.microsoft.com/fwlink/events.asp.




Event Type: Failure Audit
Event Source: Security
Event Category: Account Logon
Event ID: 680
Date: 1/16/2007
Time: 3:26:29 PM
User: NT AUTHORITY\SYSTEM
Computer: <file server name>
Description:
Logon attempt by: MICROSOFT_AUTHENTICATION_PACKAGE_V1_0
Logon account: <local username>
Source Workstation: <local vista pc name>
Error Code: 0xC0000064


For more information, see Help and Support Center at
http://go.microsoft.com/fwlink/events.asp.