There are a lot of *.tmp files accumulating under ...\Documents and Settings\All Users\Application Data\Symantec\Common Client folder and %allusersprofile%\Application Data\Symantec\Common Client folder.
Symantec is aware of this issue and Symantec is investigating the cause.
A fix will be provided in a future release of Symantec Endpoint Protection 11.
This document will be updated with the exact release information when confirmed.
Symantec Endpoint Protection 11 RU6 MP2