Hi Carl,
Thanks for the details of your log.
Does this problem arise when you try to visit the Scheduled Task page.If yes, a possible cause could be the neo-cron.xml's curroption.
Could you use a back up of this file, in case you have and reboot the server and verify.
If above case is not applicable, could you please add some information about what causes this problem to occur.
Thanks,
Anjaneai