JSI Tip 10348. A new error event is logged if you do not back up a Windows Server 2003 SP1 (Service Pack 1) domain controller in a given time period?

Microsoft Knowledge Base Article 914034 contains the following introduction:

When you back up a domain controller that is running Microsoft Windows Server 2003 Service Pack 1 (SP1), a new event error message is logged for each writable domain or application partition that the domain controller hosts. This is true if the partition is not backed up in a given time period. The time period is called a backup latency interval. You can set a registry value to specify this interval in days.