Connection to the Internet

Hello,
My internet connection is fine on the modem<, (all lights working). Right hand corner on my screen says its connected (sometimes limited). I cannot get to the internet or msn. I used a different laptop and it works fine( able to get online). I tried to do ipconfig, i get media disconnected and no valid ip, the network is not sending or receiving any data. The computer works fine in safe mode thou.
Virus?
What do you suggest, format reinstall??
I tired Norton, ad-aware, hijackthis, spybot search and destroy and even McAfee.

Thanks for your help