When installing SEPM it complains of port 1812 being in use and the word Enforcer.
If you check c:\windows\system32\drivers\etc\services you will find port 1812 is the Radius port. The Microsoft term for a Radius Server is Internet Authentication Service (IAS). Removing this service should stop the conflict.
You can also change the port that SEPM uses for RADIUS. See this document: http://service1.symantec.com/SUPPORT/ent-security.nsf/docid/2007111411152348