Airport Express for private network and WPA

I'm having trouble getting my airport express to serve as a base station for a private network (no published SSID) using WPA encryption. I carefully went through the set up, but now when I attempt to connect from my powerbook I get the error message:

The wireless network "abcdef" does not support the requested encryption method.

Has anyone else seen this problem?

Also, what really sucks is now I have to reset the airport express back to the factory settings in order to get it out of never, never land and then re-enter all my configurations. Is there an easier way of getting back into the airport express without having to wipe all the settings?

Thanks.

Following up to my post, I discovered two things. First, the recent firmware update has changed the behavior of the factory reset button on the airport express. Now what it does is adds and activates a new untitled profile in the default settings and keeps the old profiles. Kudos to Apple for implementing this improvement!

I was able to go back in to edit the old, broken profile and unclick the private network check box. This definitely works. Then I went back in and re-checked the private network box, and the unsupported encryption error no longer occurs. I even switched between networks to other base stations and back, and I can still get into the private network on the airport express. Maybe the problem boils down to setting up first as a public network, exchanging WPA encryption information, and then making the network private.