Mac can't connect to wifi network after password change I've got a Mid-2010 17" MBP freshly upgraded to 10.7.  I went to the coffee shop today to do a bit of work, but I was unable to connect to the wifi network.  I had been there yesterday(though without my laptop) and the wifi password had been changed.  I updated the password on my iPhone and iPad, and those devices have been connecting to the network with no problems.

Today when I went in with my Macbook, however, I was unable to establish a connection with the network.  I thought it was a bit strange, since it never told me the password was wrong(keep in mind, the laptop still remembers the old wifi network password), it just grabbed a self assigned IP and complained that it couldn't connect to the internet.

This is what I did in effort to establish a connection, with no success:


Removed the network in question from my saved wifi networks.  Upon attempting to reconnect nothing changed, still gets a self assigned IP, never asks for a new password, no internet connection.
Removed all entries for the network in question from the Keychain.  After removing the keychain entry, any time I reconnect to the network, the keychain entry is re-added with the old, incorrect, password.
Edited the password in the keychain entry to the new, correct, password.  This resulted in the same behavior as my first attempt, nothing new.
Removed entry from saved networks, deleted keychain entry, restarted mac.  Exactly the same as before.


So after a good 20 minutes of attempting to connect to the network, I could never even get it to prompt me for a new password(the password it has stored is definitely different than the current, correct, password for the network).  So I gave up and came home to attempt to figure it all out.

Any suggestions on how to get connected to this network with a new password?  Have I done all the right things, and should now just go file a radar on this behavior?
If you have checked both the user keychain and the system keychain for old passwords, we're left with obscure guesses.

Two things come immediately to mind (from the obscure side). 


Your mac will join any base station with that SSID. I have seen people literally setting up a second router in busy coffee shops - you have to hold the option key and make note of the mac address you have connected to and see it change to catch this.
If your wifi connects to the router wifi, it doesn't mean the dhcp server has any more addresses to lease. You will need the owner to reset or power cycle the router to see if the leases are all out and unexpired. You basicall have a great pipe connecting you to the main, but no water is flowing to you until you get a lease.