How do I make my Internet stop saying HTTP 404 every time I try acess it?

My friend got spywear on her work computer yesterday (I think). Today when she got to work it would not let her veiw any web pages it just kept saying HTTP 404 etc. So she ran a virus check, found some spywear and removed it. She then rebooted the computer but its still happening. Everytime she trys to veiw any website it says the same thing, HTTP 404 etc. I got her to check all the basic setting and they are fine, and all her work mates computers are fine and they are running off the same server, so its just her computer. So how does she fix it? Is it something simple to do with the settings or does she need to get in some real tech help?