Are you BB+ or Premier? Are you using the text.usenet.force9.net news server? news.force9.net will not work for me anymore but it is not a problem as I do not use binaries.
If BB+, you need to run a traceroute to the server and if it shows Homesurf in the hops, it needs to be referred to CS for resetting. Something to do with the capping not being compatible with the "safe surf" option in the portal.