Export Types data downloads empty ZIP file

Hi everyone, I just needed the export functionaliaty for the very first time and now noticed that it's not working…
When I hit the export button, it downloads an empty ZIP file.

My server is running the latest version of everything (WP 3.5.2, latest WP Types and Views)
(running PHP Version 5.3.18).

Do you have any idea why this could be?

Thanks for your ideas…The server has the SUHOSIN security mod installed, but usually this is not creating problems…