When moving copies of our production store to our test systems I disable all scheduled jobs using an old Extranet script.  Frequently the jobs are left enabled in Windows Server 2008R2 while being disabled in Extranet.


When opening the Windows Server 2008R2 in Server Manager (Configuration >> Task Scheduler >> Task Scheduler Library) I got an error message “The selected task "{0}" no longer exists.".  After digging into his, the solution is to delete a file which is out of synch with the registry –
C:\Windows\system32\Tasks\Microsoft\Windows\Defrag\ScheduledDefrag  (no extension)

This file is a scheduler item for regular defragmentation of the server.  After it is deleted the Scheduler is pretty reasonable to work with.  The job can be recreated if needed.

It may be a job other than “defrag”, from what I read, but has been defrag on all of my VMs.  The process is to click once on all of the objects under
Configuration >> Task Scheduler >> Task Scheduler Library >> Microsoft >> Windows 
and see which item give the error on clicking it once.