This indicates an attempt to exploit a remote unauthenticated vulnerability in the Microsoft Message Queuing RPC service.
The vulnerability is caused by an error that occurs when the vulnerable service handles a malicious RPC request. It allows a remote attacker to execute arbitrary code in the context of the service.
Microsoft Windows 2000 Service Pack 4
System Compromise: Remote attackers can gain control of vulnerable systems.
Apply the patch, available from the vendor's web site: