SAP XI - File Adapter, Sender, using FTP

Hi. On a couple of occasions we have encountered a situation where the Comms. Channel effectively stops polling, but no error is reported. Making the channel 'Inactive' and then 'Active' does resolve the issue, but I'm wondering if anyone else has experienced this, if there is a way of preventing it or effectively monitoring for this type of issue? We are using XI , SP 19.