There's a new feature in SharePoint 2010 for suppressing repeating events and errors that are written to the Windows Event Log. To configure it, go to "Central Administration" à "Monitoring à "Diagnostic Logging à Check the box for "Enable Event Log Flood Protection".

Note: Do NOT configure this if you are using Microsoft System Center Operations Manager, as there may be certain events triggered when multiple errors are written to the event log within a certain amount of time. If the events are suppressed the triggers may not execute as designed, thus limiting the benefits of using System Center Operations Manager.

For more information on configuring diagnostic logging, see the Microsoft TechNet article below:
Configure diagnostic logging (SharePoint Server 2010)