PDC Decommission/Certificate Authority questions

I'm a college student currently working on decommissioning a primary domain controller for the first time, so bear with me.

The PDC in question runs on Windows 2000, and is long past retirement. The new one runs off Windows 2003. Last week, I transfered all the FSMO roles and the global catalog, then brought the W2K Server offline without demoting it to see if there are any errors.

Lo and behold every 24 hours, I receive the following errors in the new DC's system event logs:

Event ID: 20
Source: KDC
Type: Warning

The currently selected KDC certificate was once valid, but now is invalid and no suitable replacement was found.  Smartcard logon may not function correctly if this problem is not remedied.  Have the system administrator check on the state of the domain's public key infrastructure.  The chain status is in the error data.

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

Directory Service logs:

Event ID 1864
Source: NTDS Replication
Type: Error
This is the replication status for the following directory partition on the local domain controller.
 
Directory partition:
DC=mydomain,DC=com
 
The local domain controller has not recently received replication information from a number of domain controllers.   The count of domain controllers is shown, divided into the following intervals.
 
More than 24 hours:
1
More than a week:
1
More than one month:
0
More than two months:
0
More than a tombstone lifetime:
0
Tombstone lifetime (days):
60
 Domain controllers that do not replicate in a timely manner may encounter errors. It may miss password changes and be unable to authenticate. A DC that has not replicated in a tombstone lifetime may have missed the deletion of some objects, and may be automatically blocked from future replication until it is reconciled.
 
To identify the domain controllers by name, install the support tools included on the installation  CD and run dcdiag.exe.
You can also use the support tool repadmin.exe to display the replication latencies of the domain controllers in the forest.   The command is "repadmin /showvector /latency <partition-dn>".

For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp.
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Event ID 2092
Source: NTDS Replication
Type: Warning
 This server is the owner of the following FSMO role, but does not consider it valid. For the partition which contains the FSMO, this server has not replicated successfully with any of its partners since this server has been restarted. Replication errors are preventing validation of this role.
 
Operations which require contacting a FSMO operation master will fail until this condition is corrected.
 
FSMO Role: DC=mydomain,DC=com
 
User Action:
 
1. Initial synchronization is the first early replications done by a system as it is starting. A failure to initially synchronize may explain why a FSMO role cannot be validated. This process is explained in KB article 305476.
2. This server has one or more replication partners, and replication is failing for all of these partners. Use the command repadmin /showrepl to display the replication errors.  Correct the error in question. For example there maybe problems with IP connectivity, DNS name resolution, or security authentication that are preventing successful replication.
3. In the rare event that all replication partners being down is an expected occurance, perhaps because of maintenance or a disaster recovery, you can force the role to be validated. This can be done by using NTDSUTIL.EXE to seize the role to the same server. This may be done using the steps provided in KB articles 255504 and 324801 on http://support.microsoft.com.
 
The following operations may be impacted:
Schema: You will no longer be able to modify the schema for this forest.
Domain Naming: You will no longer be able to add or remove domains from this forest.
PDC: You will no longer be able to perform primary domain controller operations, such as Group Policy updates and password resets for non-Active Directory accounts.
RID: You will not be able to allocation new security identifiers for new user accounts, computer accounts or security groups.
Infrastructure: Cross-domain name references, such as universal group memberships, will not be updated properly if their target object is moved or renamed.

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

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After some research I have found out the W2K domain controller is acting as a Certificate Authority. So...


Everything has been running without issue for over a week. Any further input on how to approach decommissioning the W2K server would be appreciated.