In the Java LiveUpdate document, since it is at the top, the JCE extention it may appear to be a fix or a patch, but please do NOT install JCE on the Mac. I have never, ever needed to do this, and may cause more problems than it solves. My machine running 10.6.8 updates from LiveUpdate without issue.
We need more information about your SEP installation (version?) and from where your Macs get updates (Symantec LiveUpdate? Internal server?). Also, is there a proxy in the environment?
A copy of the conf file (/Library/Application Support/Symantec/LiveUpdate/liveupdate.conf) and the LiveUpdate log (/Library/Application Support/Symantec/LiveUpdate/liveupdt.log) would be very helpful.
sandra