Further to my last...
I have used the Knowledge Base (errors 711 and 1068), and carried out all of the actions.
Simply put, the computer is not 'seeing' either adsl modem I connect. And I am not permitted to choose any other option than 'Connect using a broadband connection that is always on' when I attempt to set up a connection manually.
There would appear to be a configuration error of some kind.
Someone please help!
(sent from my laptop!)