The following chronological history is provided in response to Mr. MichaelD50 questions above:
iMac purchased on 5/19/12 with OSX 10.7 pre-installed.
The following Unmanaged SEP Software Components were installed on 5/27/12:
Symantec Endpoint Protection version 11.0.6300 (current version).
Symantec Scheduler version 4.03 (current version).
SymQuickMenu version 2.1.1 (current version).
SymSecondaryLaunch 4.0.3f9 (current version).
Updated to OSX 10.8 on 7/27/12.
Updated to OSX 10.9 on 10/23/13.
LiveUpdate update error emerged on or between 11/14/13 and 11/15/13.
Xcode version 5.0.2 installed on 11/15/13; LiveUpdate resumed manual and scheduled automatic updates without error.
Hope that helps!