I'd like to come up with my first HOWTO and explain how I was able to configure a secure home network using WPA2, the latest encryption & authentication standard. There are also other types of configuration (WPA1, mixed mode, LEAP, PEAP, DHCP, etc.)
Read it in this thread
Common stumbling blocks – Make sure that:
1. Ethernet cable is unplugged.
2. No firewall & configuration tool is running (e.g. Firestarter).
3. MAC filtering is disabled.
4. NetworkManager, Wifi-Radar & similar wireless configuration tools are disabled/turned off and not in use.
5. Some cards/drivers (e.g. Madwifi) do not support WPA2 (AES). Try WPA1 (TKIP) if WPA2 secured connections fail.
6. RTxxx (Ralink) drivers do not support this approach. Either install “ndiswrapper” replacing Serialmonkey's driver or visit this site.
7. Turn off “roaming” if you repeatedly fail to establish a connection.