problem with internet connection

Hi, I have a problem with one of my notebooks. My internet connection is fine, it works with other computers, but just not with one particular notebook. I read somewhere that I should go in command prompt and type command ping yahoo.com. It says Ping request could not find host yahoo.com. Please check the name and try again. When I typed in command tracert yahoo.com, it said unable to resolve target system name yahoo.com. My internet browser won't show any page, but it's weird because on the bottom right side the local network connection shows that it is connected. I used to have internet explorer 7 beta, and I had to install a root certificate at my school. Afterwards, I couldn't get online. So I uninstalled internet explorer 7 and erased the root certificate, but the problem persists. What should I do?

 

Well, I don't know if I can help or not but the first place to start is to try using the numerical address for Yahoo. Open an IE window and in the address bar type "209.73.186.238" (without the quotes) and press enter. Can you get to Yahoo's website this way?

 

Maybe here?
http://www.microsoft.com/downloads/...FF-7BFE-4336-9E65-972ED21324C4&displaylang=en

 

It turns out that it was infected with a virus, as I could not get the Norton Antivirus to show any folders I wanted to scan. So, I sent it over to get fixed, and they still haven't gotten around to it. It may take a while, but I'll try your suggestions as soon as I get it back.