LIVE UPDATE KILLS NIS-2012, DITTO AFTER REINSTALL

Lenovo ThinkPad T520, Win7-64bit...

NIS-2012 ran OK for many months, with Live Update every day.

Ran Live Update on 2012-05-17 and NIS disappeared from tray!  Would not open from Start menu.

Norton sensed a problem and ran a repair tool.  However, it did not fix the problem...still no NIS-2012.

After looking for solutions at support site, I decided to use Norton's Uninstall-Reinstall tool for a fresh start.  NIS-2012 returned.

A day later I figured Norton would have fixed the problem (duh!) and ran Live Update again.  Of course NIS-2012 disappeared.

Another Uninstall-Reinstall brought it back again.   How can we tell when NIS-2012 Live Update will be safe to run again?