I hate to ask the obvious, but it never hurts. You mentioned that you turned on WPA, I guess with the router, and that you loaded WPA_supplicant. You are also using a connection manager. Did you possibly forget to modify your profile in Ubuntu for this connection?
Ubuntu will have stored the previously valid "no security" profile for this connection, and will use that setting unless you prevent it. It will not prompt you that security settings have changed. It will just try to connect with the settings it knows- no security- and fail.
At least that is what happens with network-manager-gnome (no error message), and I consider it a shortcoming of that package. I.e., if you have no profile, it warns you of a problem, but if it sees a profile, you get no error message. The assumption is that the profile still works, and it is not checked against reality, even if you continue to fail connection with the once-functional profile.
I should report this problem to Gnome if anybody knows how and can tell me.
The workaround is to deny the connection manager access to your keyring, and hence the old profile. Then start the connection process from scratch. If you succeed, Ubuntu will ask for your keyring password and you can allow it. The new profile will replace the old one.
Last edited by SactoBob; 03-13-2007 at 02:12 AM.