If you have GSNW installed, the RPC service issues SAP type 640 broadcast every 60 seconds, even if you disable GSNW and the Sap Agent service.
If you have CSNW installed, the RPC service will perform the broadcast, even if you disable the SAP Agent.
To fix this problem, install Service Pack 5.
Use Regedt32 to navigate to:
On the Edit menu, Add Value name AdvertiseRpcService as a type REG_SZ, and set the string to No.
No turns the RPC sapping off, Yes turns it on.
Shutdown and restart your computer.
If the SAP broadcasts continue, as a trouble shooting step only, navigate to:
Select the Ncacn_spx value name and delete the string data. This totally disables SAP broadcating,
which is required by some programs.