Computer simply can\'t find an IP address, please help
 

My desktop simply can no longer find an IP address. Releasing/renewing does not work. Repairing doesn't work. My connection always says "limited or no connectivity". My wirless laptops both work, my Tivo connected to the same router works. I have tried multiple network adapters I get the same results. One weird thing is that windows is not letting me change the Windows Firewall settings. none of the choices are highlighted. Can anyone help me here?