I upgraded a late 2006 MB with 4 GB of 667 MHz DDR2 SDRAM and a 2 GHz Intel Core 2 Duo processor to Lion. Now, it can't connect to wireless. I see my local network, but I get the message, "Unable to join Wi-Fi network." The system has given me a self-assigned IP. I've tried to renew my DHCP lease manually, entering the WAN IP of the router as well as the subnet (I have another computer that I haven't yet upgraded that I was able to use to get this info). Still, no luck. Any ideas on how to resolve this? EDIT: Looking at my the MAC addresses in the wireless statistics of my router reveals that my MB is connected with about a 70% signal strength. However, it's the only of 5 current connections that does not show up in the DHCP client list. I changed the name of the computer when I reinstalled. I wonder if that's also causing an issue.