NAV 2011 - LiveUpdate "There was an error performing the update"

I have just installed Norton Antivirus for Macintosh, version 11.0.3 on a Mac PowerPC G4 running Mac OS 10.4.11.

When trying to run LiveUpdate, I get the "There was an error performing the update" message. The Symantec support webpage gives instruction how to solve this problem (for Mac OS 10.3.9). I have followed that (in the hope that it may also work for OS 10.4.11) and installed the latest Java (Java for Mac OS X 10.4, Release 9) available for my system. After restart, LiveUpdate still doesn't work.
My Internet connection is NOT through a proxy server.
Can anyone help me with getting LiveUpdate to work, please?!
Many thanks