Lion 10.7.5 gives 'connection failed' message if 'remember this network' is checked – and then still connects!

My Lion 10.7.5 macbook air gives a 'connection failed' message every time I connect to a wifi network with 'Remember this network' checked, and then still connects to the network.

When I disconnect, though, it forgets the network, so I have to re-type the password every time.

I noticed the problem after upgrading to 10.7.5. I have been traveling, and this has been consistent across Georgia, Armenia and Lebanon, in home and public networks, even when other mac users can remember these networks.

For these reasons, I think this is a problem with my notebook, not the routers/web connections.

Help!!

I don't want to manually record and re-type all my wifi passwords forever!