I'm troubleshooting a friend's MacBook Pro. She cannot connection to wireless networks - either the Airport dialog reports that the "Connection timed out" or it will connect and not receive a DHCP ip. I've reset the SMC, repaired disk permissions, every combination of rebooting the computer/router on a couple different networks, checked for updates, removed all remembered networks, cleared the keychain of all stored airport passwords, etc. I was just about ready to declare that the Airport card was dead and hope that my local Apple Store carried a new one, but I had another idea. I plugged in an Ubuntu live cd, and it connected to the wifi just fine. I'm left to assume its something in OS X? Any suggestions?