-ERR system failure: Unable to get content for Message 191399"

I am new to this email client. Came from live mail windows 2012 since i got error messages. I installed the eM client, without any issue. 1 google account (which i do not use much) and my main account from a Belgian supplier which I also use for work. I have been able (which was really important) to get all my old emails back, but regarding my Belgian account: he does not load new emails and I get this error message about every 10 min. :

08:01:20 Telenet (bartoliviers) [POP3]  Berichten aan het downloaden: Van Telenet (bartoliviers)
08:01:20    bij MailClient.Commands.Command.Process(WorkerStatus status)
08:01:20    bij MailClient.Protocols.Pop3.Pop3ReceiveCommand.Execute(WorkerStatus status)08:01:20     "-ERR system failure: Unable to get content for Message 191399"08:01:20   MailClient.Storage.Application.OperationException: Kan geen POP3 berichten ophalen vanwege de volgende reden:

any idea what I can do to solve this?