seems like you are using 11.x
that reached EOL wont be any updates,
Upgrade to 12.1.5 as soon as possible.
Symantec Endpoint Protection 11.0.X EOSL
https://www-secure.symantec.com/connect/forums/symantec-endpoint-protection-110x-eosl
if you are already on 12.X then the problem is with your Proxy, from the log It says Return code =4, check the proxy settings in the SEPM and also make sure you can reach symantec website
Error: "LiveUpdate encountered one or more errors. Return code = 4" in Endpoint Protection Manager
http://www.symantec.com/business/support/index?page=content&id=TECH103112