The way that the nonce is added to the url for the XML file that contains address coordinates causes it to be an invalid url:
http://www.example.com/?download=address-xml& amp;address-xml=aaaaaaaaaa& amp;&member_type_id=1,2,3&small_group=0
Note the & amp; mixed in with straight & in separating the variables in the url
(NB edit: I have added a space into & amp; to stop it being parsed by the forum software)