Is the SEP cliiet running? What is the Status showing on the client GUI? Is this a new install? Any errors in the Windows event viewer?
You may have corrupt definitions. See -
How to clear out corrupted definitions for a Symantec Endpoint Protection Client manually
http://www.symantec.com/business/support/index?page=content&id=TECH103176
If this is not the case, try running a client repair from Add/Remove Progarms.