Some web pages won't open/display

I have recently 'upgraded' from the standard Orange boradband to the combined broadband + home line package. I changed on 24 December and, despite continiuing to use my BT Voyager 2000, experienced completely relaible email and internet service.

3 days ago I stopped being able to load/view lots of websites including Orange (my ISP's own website!!), BBC, Microsoft and many others. Yet there are loads of websites (obviously inlcuding this one) thay I can load/see. I have carries out all the advice from Orange Technical help and checked with BT Voyager Help that all is OK with the router - it is. A line test determined that, according to Orange, there is no fault on the line. The router is set to the correct DNS server.

I don't think the problem is with Explorer as I have the same problen when using the internet on a laptop via the same router.

I am connected to the Orange server as I can send and receive emails OK.

When pinging some websites I can't view (Orange & Microsoft) I get "Request timed out" four times and "Packets: sent = 4, Received = 0, Lost = 4 (100% loss)".

I am due to have the Livebox installed next week: will this solve the problem?