On exchange 2000, 2003 or 2007 you may witness the following error multiple times in the application logs on your exchange server.
Event Type: Error
Event Source: MSExchangeIS Public Store
Event Category: Replication Errors
Event ID: 3093
Time: 1:56:41 PM
Error -2147221233 reading property 0x674b0014 on object type tbtMsgFolder from database "First Storage Group\Public Folder Store (AUSMAIL01)".
This happens when diagnostics logging is set to MAX for the MSExchangeIS Public object, Replication category. This happens by design.
When you see "-2147221233" or "0x8004010f" this means "No errors were found". When logging is set to max exchanges logs every read even when it was not an error. This was made by design.
Recently Microsoft has documented this in a KB article which can be found: