Hello,
Take a close look at the logs you're reviewing where you see these alerts...if the IP address(es) are external, there's not much you can do...the nature of the internet is to allow unsolicited attempts for communication.
If the communications are coming from external sources, you can certainly block those IP addresses at the perimeter firewall, and other things such as leveraging intrusion prevention (assuming you've got that, or it's part of the perimeter firewall).
If the attacks are coming from WITHIN your network, you'll need to do some seluthing to get to the bottom of what's actually attacking and deal with it. My gut, however, leads me to believe that your logs show external IP addresses.
Script kiddies out there are constantly running programs that will try to use exploits on machines...odds are low that you're specifically being targeted.
If the IP addresses in the logs are external to your network, the only way you can completely block the alerts is to configure your perimeter firewall to not allow incoming external traffic to this machine...which, I suspect, would completely negate the usefulness of the server itself.
Also, Please check the Symantec Article below and get assisted.
OS Attack: MS Windows Server Service RPC Handling CVE-2008-4250
http://www.symantec.com/business/security_response/attacksignatures/detail.jsp?asid=23179
Microsoft Windows Server Service RPC Handling Remote Code Execution Vulnerability
http://www.securityfocus.com/bid/31874/solution
You may be also interested to have a look at this Thread:
https://www-secure.symantec.com/connect/forums/multiple-attacks-showing-sepm
Hope that helps you to upload all the updates on the system.!!