I have the same problem of Lenovo T60, T400, T500.
I can connect the first time to the hidden wlan, but when I try to connect again using the previous settings the network manager popup has the connect button disabled. I tried disabling keyring with no success. I have also tested with Fedora 12 same HW, same release of NM and it works fine, it seems an Ubuntu problem.
I have the same problem of Lenovo T60, T400, T500.
I can connect the first time to the hidden wlan, but when I try to connect again using the previous settings the network manager popup has the connect button disabled. I tried disabling keyring with no success. I have also tested with Fedora 12 same HW, same release of NM and it works fine, it seems an Ubuntu problem.