Replication Issue

All of a sudden one of my DC's has quit making outbound replications and will not accept inbound replications.  The server is running 2003 Server w/ SP1.  My initial thought is that SP1 is the problem but I have two other DC's that are replicating to one another without error and both are 2003 w/SP1.

The event logs state to check DNS and that the servers are all online, which they are.  I can access the sysvol share using DNS and IP address from each server.  RPC is running and the firewall that is a part of SP1 is disabled.  I've checked and re-checked AD Sites & Services to make sure the correct topology information is listed, which as far as I know is correct.  We have a hub and spoke network and our 4 remote sites, with DC's are all configured as site links, which include the main hub and the remote site.  I've turned off Bridge all Site Links since our network is not 100% fully routed (something I plan on changing very soon).  At any rate the server can communicate just fine with the server it needs to replicate to / from but replication still isn't happening.

Here are my event log entries:
Event ID:1311
Source: NTDS KCC
The Knowledge Consistency Checker (KCC) has detected problems with the following directory partition.
Directory partition:
There is insufficient site connectivity information in Active Directory Sites and Services for the KCC to create a spanning tree replication topology. Or, one or more domain controllers with this directory partition are unable to replicate the directory partition information. This is probably due to inaccessible domain controllers.

Event ID: 1865
Source: NDTS KCC
The Knowledge Consistency Checker (KCC) was unable to form a complete spanning tree network topology. As a result, the following list of sites cannot be reached from the local site.
CN=<site name>,CN=Sites,CN=Configuration,DC=<domain>,DC=com
CN=<site name>,CN=Sites,CN=Configuration,DC=<domain>,DC=com
CN=<site name>,CN=Sites,CN=Configuration,DC=<domain>,DC=com
CN=<site name>,CN=Sites,CN=Configuration,DC=<domain>,DC=com

Event ID: 1566
Source: NTDS KCC
All domain controllers in the following site that can replicate the directory partition over this transport are currently unavailable.

CN=<site name>,CN=Sites,CN=Configuration,DC=<domain>,DC=com
Directory partition:
CN=IP,CN=Inter-Site Transports,CN=Sites,CN=Configuration,DC=<domain>,DC=com

This is listed once for each site that is defined.

When running replmon I see the following error:

Replication Failure: The remote procedure call failed and did not execute

It list that error for each of my AD Sites that are defined.  From the testing I've done RPC seems to be configured correct.  NETDIAG and DCDIAG did not return any obvious errors.  I'm not sure where else to look.  Any suggestions?

Thanks in advance.
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liquid22Author Commented:
Well - looks like I resolved my issue.  It was directly related to SP1.  As soon as I uninstalled the service pack replication began as normal.  Either I'm overlooking something or Microsoft still has some issues to address.
Closed, 250 points refunded.
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