Exchange 2003 public folder replication error

We have an Exchange 2003 server that reports "Error 1129 occurred while processing a replication event" every 5 minutes. It is reported for one specific public folder. I have stopped all public folder content replication at the top level of Exchange but the error still continued in 5-minute interval.
If I look at the replication settings for the folder (and any other public folders), under "replicate content to these public stores", it lists the public folder itself and the Exchange server itself. We have a front end server but no other Exchange server on the network.
Most of the articles I can find refer to replication between Exchange 2003 to Exchange 2007 but that does not apply in our case.

I am wondering if anyone has a solution for this.

Thanks much.
Akira