When you view the first event in an event log on a Windows Server 2003 computer that has SP1 (Service Pack 1) installed, and then press the UP ARROW in Event Properties to move to the last event, you receive:

The event log file is corrupt.

NOTE: If the cache is successfully discarded during this process, you receive:

This log file is updated during a log reading process.

This behavior may occur if the event logs are frequently updated, moving the access pointer in an event log file.

To workaround this issue, close and reopen the Event Viewer to refreshes the event log entries and access pointer.

NOTE: When working properly, you should receive:

You have reached the beginning of the event log. Do you want to continue to the end?

NOTE: See How do I to use Event Viewer to view and manage event logs in Windows XP?