So I have a weird thing that's just happened this afternoon. I have a cable modem going into airport extreme, which provides a wireless signal as well as an ethernet connection to the Mac Pro. For some reason, this afternoon the Mac Pro suddenly can't get online, despite the fact that the airport seems to be working (airport utility shows no problems and I'm online right now wirelessly, via my laptop). I tried connnecting the Mac Pro via airport, but exactly the same symptoms occur as when connected via the ethernet cable - it shows that it is connected to the network and gives green lights, but can't bring up any web pages. iTunes also cannot connect, so it's not a problem with the browser. I even tried going into advanced network settings and making sure all of the airport settings were the same between the laptop and the Mac Pro. They are, yet the Mac Pro can't get online. I've tried both of the ethernet ports on the Mac Pro and all three on the Airport Extreme. I've tried switching ethernet cables. Running the Network Preferences diagnostics (on both ethernet connections, and the airport connection) gives me green lights for Ethernet, Network, and ISP, but can't confirm Internet or Server, which is no surprise, given all the other symptoms here. I confess that network settings and various internet protocols are my weak point here, but even so, this seems weird. I'm at a loss. Suggestions?