Hi,
Try doing a repair for the SEP installation through Add/Remove Programs.
Also try clearing all the definitions, preferably using Rx4defsSEP Utility. If you don't have the utility contact tech support to get it.
Using the "Rx4DefsSEP" utility
http://www.symantec.com/docs/TECH93036
You may also try clearing the definitions manually by following the article below.
How to clear out definitions for a Symantec Endpoint Protection 12.1 client manually
http://www.symantec.com/docs/HOWTO59193