Check your system clock to make sure the date is correct when you first turn on the computer. Also, run the Subscription Status Check (Support > Subscription Status). If this corrects the issue, your clock may be shutting down while your PC is off and Norton is switching off because it cannot verify the subscription because of it.
Please feel free to come back anytime you desire and ask about anything you are unclear about. Also deifinately come back and continue in this thread if the situation occurs again.