Some information regarding the change on the Symantec Management Agent service to use "Automatic (Delayed Start)" mode:
The Symantec Management Agent (SMA) service is configured to start as an "Automatic (Delayed Start)" service. This change has been made to allow smoother user login when the SMA agent does not interfere with the user during login by running tasks or policies or causing a machine shutdown. Delayed services are started 2-3 minutes later than "Automatic" services, user is usually already logged in at this time.
The "Delay on boot" feature has been redesigned because it caused a few problems with Windows and 3rd party software.
On Vista or greater "Delay at System Boot (secs)" registry entry is not used anymore. AeXNSClient service's startup type is now "Automatic (Delayed Start)" instead of "Automatic", so Windows itself provides the delay after the machine restart. If 3rd party software or user wants to start the service earlier than Windows starts it they can do that manually or via API - the service will start immediately and will be ready to accept COM calls after entering the "running" state.”