I had an issue where I would run a Task like 'Update Client Configuration', but the NS would show a ‘Failed’ status after a few hours.  On the client, it would show 'Success - return code 0'.  The reason it failed was because the 'Altiris Client Task Data Loader' service was not running.  I tried starting the service, but got a ‘Error 1053: The service did not respond to the start or control request in a timely fashion’. 

The solution for me was to follow the instructions provided by K. Kennedy at https://www-secure.symantec.com/connect/forums/altiris-client-task-data-loader-service-wont-start.