BT wont find any pages, PLZ help

i recently had some problems with viruses on my computer and had to ro format the whole of my computer i found all of the viruses. i am on BT broadband but it lets me connect but is lettin me view only about 5 pages befor it starts showing the "page cannot be displayed" sign
it also keeps tryin to log on like i am still on dial up connect but im not, i dont know if i need to update a later version of the BT broadband software if anyone can help me were to find the latest software or anybody is aware of any problems that my be causing this i would be truly grateful
thanks to anyone who can help
Hannah

Is your dail-up modem still connected to the PC, or is it in-built?