Mountain Lion is stuck with "See network administrator" when joining Wi-Fi network
I faced a similar issue on my MacBook Pro with one particular WIFI connection. It was giving me the "Connection time out" error message.

I was able to workaround it by:

1) Removing the WIFI connection: System Preferences > Network > WIFI > Advanced > Select the relevant connection and click the "-" sign > Click "Show All" or close the window.

2) Adding the connection manually: System Preferences > Network > WIFI > Advanced > Click on the "+" sign > Enter the connection settings manually.

This has worked for me and that particular connection never gave me issues afterwards.

Hope this helps.