Hello,
As per the Logs, we see errors as below:
21/08/2012, 08:03:53 GMT -> Progress Update: DOWNLOAD_FILE_START: URL: "http://liveupdate.symantecliveupdate.com/sesm$20antivirus$20client$20win64_12.1_english_livetri.zip", Estimated Size: 0, Destination Folder: "C:\ProgramData\Symantec\LiveUpdate\Downloads"
21/08/2012, 08:03:53 GMT -> HttpSendRequest (status 404): Request failed - File does not exist on the server.
21/08/2012, 08:03:53 GMT -> Progress Update: DOWNLOAD_FILE_FINISH: - NOTE - URL: "http://liveupdate.symantecliveupdate.com/sesm$20antivirus$20client$20win64_12.1_english_livetri.zip", Full Download Path:
What happens if you run the Liveupdate from SEPM?
Are you using any Proxy? If yes, please ensure the Proxy settings are set properly on the SEPM server-
https://www-secure.symantec.com/connect/articles/how-configure-proxy-settings-symantec-endpoint-protection-manager-sepm-121
Also, make sure you have proper rule on the proxy to allow all this IP which may resolve the issue.
Secondly,
Open IE--> tools--> Internet options --> security --> security level to this zone.
Changing the IE security option to middle or low can resolve this issue.
Did you try updating the SEPM with the .jdb file and check if the SEPM gets updated?
How to update definitions for Symantec Endpoint Protection Manager (SEPM) using a .jdb file
http://www.symantec.com/docs/TECH102607
Hope that helps!!