Hello,
Have you read this KB?
Event ID 13: "SescLU - LiveUpdate returned a non-critical error. Available content may have failed to install."
http://www.symantec.com/business/support/index?page=content&id=TECH91615
Incase, if the Steps doesn't help, I personally would request you to :
1) Uninstall Symantec Endpoint Protection Client along with Liveupdate from the machine.
2) Delete all the Leftover files of Liveupdate like:
On Windows 2000, XP and 2003:
3) Install the Latest version of Endpoint Protection Client (11.0.6300)
Follow the Article to Migrate to the Latest version :
Migrating to Symantec Endpoint Protection 11.0.6300 (RU6 MP3)
http://www.symantec.com/business/support/index?page=content&id=TECH155655
I am sure that would work for you.