Uhm, that reminder was added some weeks ago. It seems that your server doesn't recognise that cron is running in your system. And that's very strange because the functionality to detect it is independent from the controller cron application (Windows Cron, unix...).
Are you 100% sure that it's running? Do you receive a copy of messages in your server's forums?
Ciao
Backup and restore
Cron Error
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