i have found the best solution to this problem was to get rid of bt and find a proper company that supplies a service that works, bt will not help in any way, i had the same problem with it being unwatchable for£50 a month and could not find a solution in weeks of searching for a fix,
I probably should have come back on this, but mine eventually sorted itself out, up to a point. I get an occasional freeze in IE11 after a couple of hours. Firefox is dead slow, but I do have a lot of plug ins, extensions and bookmarks, and Chrome sometimes works, sometimes requests Silverlight. Following BT's deal with Sky, however, next year I'll be watching on my Now tv box.