Internet connection but no access.

Hi I have been having trouble on one of my computers, The machine is connected to the internet, but it does not seem to use its connection. I tried opening Internet explorer but it didnt work. I even tried using safari which still didnt work. Every time it says "Unable to connect to server". I even went so far as to get PDANet on this unit, hoping that would fix the problem, but it will not even use the internet off my phone. I've also ran tests in the cmd prompt and it reported no loss. I am confused!