I have an iMac 7,1 (2007 Alu C2D 2.0 Ghz) running Snow Leopard (10.6.7) and occasionally when I wake my iMac from sleep the ethernet card as a self-assigned IP address and won't connect to the Internet. It's ridiculously annoying as I have to restart my computer or toggle DHCP on and off over and over again. I also have Internet sharing on, so that my iPhone can use WiFi in my room. Does anyone else have the same problem? Is this a problem with my ethernet card that I should take to the Apple center to get fixed up?