Hi,
How to determine if virus definitions of Symantec Endpoint Protection client (SEP) 11 or 12 Small Business Edition, are corrupted
http://www.symantec.com/docs/TECH97677
If you think definitions are corrupted follow this article
How to clear out corrupted definitions for a Symantec Endpoint Protection client manually
http://www.symantec.com/docs/TECH103176
You can get the Rx4Defs tool by calling Symantec support.
http://www.symantec.com/business/support/index?page=content&id=TECH93036&locale=en_US