The following message is displayed under "Shared Schedules":
"There are 1 missing tasks for schedules in Windows Task Scheduler Library"
ITMS 8.x
Go to Task Scheduler (usually under Start>All Programs>Accessories>System Tools) and find NS.Weekly. Run it and it should go and recreate any missing scheduled task.
If the message is still present and you are still missing a scheduled task, please refer to KB 161324