As per Microsoft: "This event can be an indication of a larger problem. There could be accompanying public folder replication issues. The Microsoft Exchange Information Store service might be unable to access Active Directory. Many errors correct themselves, so take action only if a problem persists during several directory synchronization cycles". See MSEX2K3DB for more details.
Build a great reporting interface using Splunk, one of the leaders in the Security Information and Event Management (SIEM) field, linking the collected Windows events to www.eventid.net.
Obtain enhanced visibility into Cisco ASA firewall logs using the free Firegen for Cisco ASA Splunk App. Take advantage of dashboards built to optimize the threat analysis process.