My wife's mac-mini (running Leopard) exhibited a strange problem yesterday. She could not access www.youtube.com, but other web sites seemed fine. There was nothing wrong with the youtube site -- I tried it from another computer (they are all behind a lynxsys router running NAT) and had no problems, but from her computer I could not even ping it. I finally traced it to the fact that en0 had two IPv4 IP addresses. One was the expected 192.168.1.x address and the other was a class A address 74.x.x.x. It just happens (coincidence?) that the youtube address is also a 74.x.x.x address, so I guess the second address upset the routing to youtube. I removed the address using 'ifconfig -alias' and that fixed the problem, but of course that fix only worked until I rebooted (at which time it came up with a different second address: 204.x.x.x). I tried switching from dhcp to static, but still had the problem. I would really like to (a) fix this problem and (b) understand what is causing it. Any ideas?