Norton Safety Minder stops running

Have had Norton Safety Minder on my computer and my son's computer since February 2012.  It has been great until about a month ago.  It continually stops running on my son's computer.  I have been through technical support with a rep remotely uninstalling and reinstalling twice and it still stops running.  I know that he doesn't know the password as the times it actually is running and his time is up I need to put in to extend time.  I have the premiere subscription and am concerned that he is not being monitored.  What can be causing this and how can I fix/correct this problem so that I feel comfortable with him using the internet and being monitored for time.