As Ambesh mentioned before, it does seem like an issue connecting to Symantec Liveupdate on the internet in general as per the below log entries:
9/24/2013, 6:03:47 GMT -> Progress Update: TRYING_HOST: HostName: "liveupdate.symantecliveupdate.com" URL: "http://liveupdate.symantecliveupdate.com" HostNumber: 0
9/24/2013, 6:03:47 GMT -> Progress Update: TRIFILE_DOWNLOAD_START: Number of TRI files: 0 Downloading LiveUpdate catalog file
9/24/2013, 6:03:47 GMT -> LiveUpdate will download the first Mini-TRI file, liveupdate_3.3.100.15_english_livetri.zip
9/24/2013, 6:03:47 GMT -> Progress Update: DOWNLOAD_BATCH_START: Files to download: 1, Estimated total size: 0
9/24/2013, 6:03:47 GMT -> Progress Update: PRE_CONNECT: Proxy: "(not-available)" Agent: "Symantec LiveUpdate" AccessType: 0x0
9/24/2013, 6:03:48 GMT -> Progress Update: CONNECTED: Proxy: "(not-available)" Agent: "Wr73y+csROTJxfcw3Tc+X1+0pbIPCtBUgAAAAA" AccessType: 0x0
9/24/2013, 6:03:48 GMT -> Progress Update: DOWNLOAD_FILE_START: URL: "http://liveupdate.symantecliveupdate.com/liveupdate_3.3.100.15_english_livetri.zip", Estimated Size: 0, Destination Folder: "C:\ProgramData\Symantec\LiveUpdate\Downloads"
9/24/2013, 6:03:48 GMT -> Unable to find the property 'PREFERENCES\MAX_LIVETRI_SIZE' in settings file; using default: 1048576.
9/24/2013, 6:04:09 GMT -> CSendHTTPRequest::SendRequest - Timed out while communicating with server.
9/24/2013, 6:04:09 GMT -> Progress Update: DOWNLOAD_FILE_FINISH: - NOTE - URL: "http://liveupdate.symantecliveupdate.com/liveupdate_3.3.100.15_english_livetri.zip", Full Download Path: "C:\ProgramData\Symantec\LiveUpdate\Downloads\liveupdate_3.3.100.15_english_livetri.zip" HR: 0x802A0045
9/24/2013, 6:04:09 GMT -> HR 0x802A0045 DECODE: E_UNABLE_TO_REACH_SERVER
9/24/2013, 6:04:09 GMT -> Progress Update: DOWNLOAD_BATCH_FINISH: HR: 0x802A0045, Num Successful: 0
9/24/2013, 6:04:10 GMT -> HR 0x802A0045 DECODE: E_UNABLE_TO_REACH_SERVER
9/24/2013, 6:04:10 GMT -> EVENT - SERVER SELECTION FAILED EVENT - LiveUpdate failed to connect to server liveupdate.symantecliveupdate.com at path via a HTTP connection. The server connection attempt failed with a return code of 1814, LiveUpdate could not retrieve the catalog file of available Symantec product and component updates.
I think it's worth noting that while the proxy checks came back with a 0x0 result, the LU Client still appreared to be trying to connect to a proxy server as higlight in italics above. If no proxy is in use, I'd actually expect that to say "null" (as mine does).
Do you use a proxy? What is configured in the LU proxy settings for the SEPM and do these differ from those in the LU settings in the Control Panel?