Well, dont really know what to tell you beyond the obvious. Check your browser, firewall, etc., if all else fails get in touch with the Oryx people.
However, for the record, not having an IDE to model BPMN 2 processes shouldn't stop you. You can create one in a simple XML editor. Grab one of the BMPN examples in the JBPM sample set to start.
Good luck (to all of us ;) )..