Works for me, just tried it (OS X 10.5.8, FF 3.5.5), also outside the Quark network. Weird.
Please hit the Contact button above this post and send me an Email. I'll mail you the XTensions then.
Sorry for the trouble.
Best
Matthias
Matthias Günther
Senior Product Manager
Quark Software Inc.(Please note: As I am traveling frequently, answering your post might sometimes take longer)
Want to easily publish for the iPad, using high-fidelity designs with stunning interactivity? See here: English:
http://youtu.be/Gldk5lvXXTA French:
http://youtu.be/nsgB4Q7lQzg German:
http://youtu.be/lecdenqaUGY Italian:
http://youtu.be/wjBpYZsF-8s
Need help? Contact Quark's support:
http://support.quark.com/contact_us.html
Please don't install the newest update 10.7.3 of Mac OS X Lion yet. For details please see here: http://goo.gl/AzKeR