This is a know problem: from support Symantec (thanks to them)
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It appears to be a known problem (at least in review right now).
When you select option to run Wake On LAN task Notification Server creates Scheduled Task named something like
NS.Run WOL Task for Managed Delivery Policy
GUID on Schedule.{
GUID}
If policy is disabled, task remains the same and keep running according to schedule. It will be removed only if you disabled the option to run WOL and save policy, which you already did.
Second problem with this is if you delete this Managed Delivery Policy and do not not disable/save WOL task it will be orphaned, it will not appear anywhere in reports, but will keep running and report error
( Exception Details: Altiris.NS.Exceptions.AeXException: The specified GUID does not refer to a registered class (GUID:00000000-0000-0000-0000-000000000000)
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Happy for me, I never delete any Altiris items. I allways "deactivate", move "trash sub-folder"... So we can apply easily the workaround.
Be aware if you change the "target" of the deactivated policy, PCs out of the target list continue to receive the WOL.
So Just deactivate the WOL and save.
Hope to get this solved next SP (CMS7 sp3 ?) not sure, but probably corrected from an update the SMP part (next sp5?)... ;-)