Thank you for your prompt reply.
I've customized the MDNS 6.5 template (comes with the MDNS SDK) so that the MDNS server controls get initialized server-side on page load (instead of during an out-of-band callback) and that it includes a simple FlyTreeView and FlyContextMenu. If FlyTreeView.visible is set to false, everything works fine. Setting the attribute value to true causes the problem described before. A lot of javascript errors appear because of the MDNS scripts emitted do not longer contain line breaks so everything is commented out.
I don't seem to be able to upload a 781kB zip file, so I've send you the file by email.