read these articles
Disk Space Management procedures for the Symantec Endpoint Protection Manager
http://www.symantec.com/docs/TECH96214
.dat files accumulating in the Inbox folder on SEPM
http://www.symantec.com/docs/TECH95166
Content Update files in the \Program FIles\Symantec Endpoint Protection\LiveUpdate are growing in size
http://www.symantec.com/docs/TECH105695
How to clear out corrupted definitions for a Symantec Endpoint Protection Client manually.
http://www.symantec.com/docs/TECH103176
Symantec Endpoint Protection Manager directories contain many .TMP folders consuming large amounts of disk space
http://www.symantec.com/docs/TECH98416