The not being able to get back online I would definitely say was an authentication issue.
However it is really strange that certain websites are unavailable and why.
Those sites that arent available are they all UK sites.
Included in UK sites would also be any worldwide sites but hosted at the likes of akamai (london).
My hosts direct peer with all the major ISPs, so you shouldnt have to go out to the general www to reach my server. BT.com and sky news (via akami) also direct peer.