Right, you could try this, it helped my mate,
Basically you want to change your dns server settings to use opendns rather than bt's default servers.
The addresses are here if you know what your doing,
208.67.222.222
208.67.220.220
For BT Home hub 2.0, W7 users,
Go to my computer, right click 'network' on the left hand side, choose 'properties', left hand side click 'change adapter settings' right click 'local area connection', choose 'properties' then double click on 'internet protocol version 4 (TCP/IPv4)
And enter in the following,
This can work for pretty much anyone but make sure the 'default gateway' ip is the same as your routers, which you can find out by typing 'cmd' into search on your start menu, click on 'cmd.exe' once loaded type 'ipconfig' and look for the 'default geteway' IP (number) and use that number.