I am using Idea 3.0.5 and I have this problem...
Since some moment (don't know exactly),
during editing the XML files where are declared namespaces like
the Idea does not shos me the popup, which enables to download the
schema located at that URL ,
only shows me popup "URI not registered (IDE Options | Resources)..
Popup Hints are ON,
I know I can register it using (IDE Options | Resources) but I is not
as fast and easy like that popup, which downloaded schema and registered
it automatically...whats wrong? :(