Problem with team folder

Hi,

we have several teams and use the team folders to store ASCII files for data upload into BPC. When trying to access one of the folders the users now get this message

When they click on OK the folders open but is empty even. As the upload happens monthly we know that this did work last month and that there should be files in the folder.

Does anyone know what this error means and how we can solve it?

Thanks,

Arnold