I think this error is caused when the scheduler tries to run the job publishing versions (don´t know the exact translation atm), that is by default run every minute. If this job not could start due to some reason, the error occurs. Try to check your database for jobs that is set to true, but started a long time ago. Set them to false. This will only make them reevaluate themselves when triggered again. Then, check that you don´t have any scheduled job that takes too much time to complete. Best practice in scheduled job is to run them in a separate thread to avoid those kinds of errors.
Hope you got some help of my post. :)