[X-Newbies] Can't connect to internet?

[Mark Taintor]

My son's Macbook running X.4.11 can no longer connect to the wireless 
network in our house. Running the network diagnostics from within 
Safari, he gets the following message:

Cannot find server
This computer appears to have a working internet connection but cannot 
find "Livepage.apple.com". You may have typed the address incorrectly.

No other pages will load either.

Going into System Preferences->Network, it says that the computer is 
connected to the internet via Airport.

Any ideas of what's going on with his machine? He's repaired 
permissions, run the maintenance scripts. Any other ideas to try?
Thanks,
Mark