I always find repetitive event 4004 in event viewer. Log Name: Application Source: MSExchange Availability Date: 9/18/2011 5:25:24 PM Event ID: 4004 Task Category: Level: Warning Keywords: Classic User: N/A Computer: XXX Description: Unable to find a public folder server for organizational unit (OU). The service will attempt to find a random server, which may take a longer time to service the request. What is the matter of it ?

Have you seen: http://blogs.msdn.com/b/dgoldman/archive/2008/02/02/looking-up-free-busy-information-in-a-mixed-org-e2k3-e2k7-will-return-a-4004-error.aspx

Hi Dkjyku, Any update? Please try the suggestioin in the blog to correct user's LegacyExchangeDN or add a Public Folder store and the related replication. note that, after adding the LegacyExchangeDN, you need to add X500 address and update the profile for the problematic user. If the issue continues or if there is anythine unclear, please let me know.Fiona