Can't "see" modem

about 3 days ago mr computer at home became unable to see
our cable modem. Everything checks out with the cable
company is being OK on their end. My computer tries to
load in explorer- the address for the home page comes up
(msn.com) at the top of the screen but at the bottom it
says it is looking for www.incredifind.com. So it just
sits there and nothing ever happens. I have Norton anti-
virus and when it tries to download new virus updates it
says it can't make an internet connection.
Any ideas?