Strange issue - no connection to the internet

I use BT broadband and for the last few days whenever I try to go to the RSPB forum it brings up the no connection to the internet message and sometimes takes a couple of attempts to bring up the forum page and even then it sometimes brings the no connection back up while browsing through the forum.  It only does it with the RSPB forum, no other sites and I've had other sites up at the same time that have worked fine.  Didn't think much of it at first but it keeps happening so thought I'd post a message in case others are having the same problem,