Airport autoconnect not working?

[bibulb]

I've got a dual-USB iBook G3 (running Tiger with all updates) with an AirPort (original) card installed, and also an AirPort Extreme N base station with WEP (Transitional Security Network) for security. (IIRC, this essentially provides WEP for those backwards systems that can't do WPA/WPA2 but WPA for those who can.) I've got three other machines that log in under WPA2 Personal with no issues.
When selecting my network from the AirPort menu, the ONLY option in the security menu in the drop-down box is WPA Personal. When I enter the WPA password and click "OK", I get a dialog box stating "There was an error joining the AirPort network 'MySSID'," with choices of "OK" (dismisses dialog) or "Try again" (repeats process).
When I select "Other..." from the AirPort menu, type in the SSID and select EITHER "WEP Password" OR "WPA2 Personal" and enter the passkey, it logs me in. When the machine goes to sleep, though, it drops the link and does NOT remember it to bring it back up.
However, I am also using this at a public hotspot with no security. (It's a hospital - they assume that if you CAN use it, you're entitled to do so.) It remembers the hospital's hotspot from sleep/wake to sleep/wake.

I've tried building the "preferred networks" list in the Network pane in System Preferences, with the same issues. (And it took care of the hospital's hotspot with a manual setup before I even took it there.)

Any ideas how I can have the iBook log into the home station automatically? Is there something I'm missing in setup that's crucial to this?
(Having to manually re-log in each time is merely annoying, but it IS annoying. I want it to be less annoying.)