Comcast Xfiniity NSS fails to launch from Taskbar

Why sometime February 7 - 14, 2015 did Comcast Xfinity's Norton Security Suite stop launching from my Taskbar, Desktop and Start Menu?
Uninstalled then installed from Comcast Xfinity's Norton web page. Not fixed.
Task Manager still reveals two Background Processes identically named "Norton Security Suite (32 bit).
Computer has Windows 8.1 Pro. Shortcut Properties show Target as "uistub.exe" modified 10/8/2013 in folder "...\Engine64\21.1.0.18".
My other computer has Windows 7 Pro with Norton launching correctly: Properties show "uistub.exe" modified 9/21/2014 in folder "...\Engine64\21.6.0.32".