XP domain login errors

Prior to upgrading our SBS 2000 server to SBS 2008 I am upgrading all of the client PCs to Windows XP Pro (I don't like Vista).

This is going fine apart from a couple of strange issues.

Firstly, I get the following events on most, if not all, XP Pro workstations but not existing 2000 workstations that I haven't yet upgraded:

Event Type:      Error
Event Source:      Userenv
Event Category:      None
Event ID:      1054
Date:            18/02/2009
Time:            11:23:32
User:            NT AUTHORITY\SYSTEM
Computer:      COMPUTERNAME
Description:
Windows cannot obtain the domain controller name for your computer network. (The specified domain either does not exist or could not be contacted. ). Group Policy processing aborted.

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


Event Type:      Error
Event Source:      AutoEnrollment
Event Category:      None
Event ID:      15
Date:            18/02/2009
Time:            11:23:34
User:            N/A
Computer:      COMPUTERNAME
Description:
Automatic certificate enrollment for local system failed to contact the active directory (0x8007054b).  The specified domain either does not exist or could not be contacted.
  Enrollment will not be performed.

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


Event Type:      Error
Event Source:      NETLOGON
Event Category:      None
Event ID:      5719
Date:            18/02/2009
Time:            11:23:32
User:            N/A
Computer:      COMPUTERNAME
Description:
No Domain Controller is available for domain DOMAINNAME due to the following:
There are currently no logon servers available to service the logon request. .
Make sure that the computer is connected to the network and try again. If the problem persists, please contact your domain administrator.

The XP workstations are not all the same hardware so this kind of eliminates the old NIC driver solution.

I don't know if this is a coincidence or not but local Outlook mail seems to be slow on these boxes. I had not been seeing any errors in the SBS 2000 event viewer, however last night out of the blue I saw:

Event Type:      Error
Event Source:      MSExchangeDSAccess
Event Category:      Topology
Event ID:      2102
Date:            22/02/2009
Time:            00:00:02
User:            N/A
Computer:      MYSERVER01
Description:
Process MAD.EXE (PID=2888). All Domain Controller Servers in use are not responding:
MYSERVER01.MYDOMAIN.local