The user who scheduled the job is not active.
Check in Administration > Resources or run the following query:
select id, user_name, user_status_id, first_name, last_name, email_address, last_updated_date, last_updated_by, last_logged_in_date
order by last_updated_date desc
The resource status ids are:
200 - Active
201 - Inactive
202 - Lock
Check the account status of the user who scheduled the job.
Delete the job schedule if the user is no longer active or set the user to active if they have been locked/inactive.