getting onto ntlworld.com and downloading emails

Hi,
I dont know what is going on with my computers at the moment!

I have BT broadband and have a belkin modem/router and none of my computers can either get onto www.ntlworld.com or download emails from NTL (pop.ntlworld.com)
I used to use NTL as my dial up ISP so still keep my email address.

Every other website on the internet works!!

This stopped working on Friday and hasnt worked since (worked fine before this).
If I go to my friends house who has a different router but is still on BT I can do everything as normal.

Has something gone wrong with my router settings or what is going on???

I hope someone can help

Thanks a lot

Luke