When you right click the subject task and press Properties, you receive:
The attempt to retrieve account information for the specified task failed; therefore, the task did not run.
Either an error occurred, or no account information existed for the task.
The specific error is: 0x8007000d: The data is invalid.
When you press OK, you notice that the Run As line is blank, or dimmed. The Run line is also dimmed.
This behavior will occur if you schedule the task in the context of a local computer account, and subsequently run DCPROMO to make the server a domain controller. In this scenario, the local account is no longer available.
To resolve this problem, delete the task and reschedule it using a domain account.