How do I solve a problem with Appointments+

Hi, I've installed and configured Appointments+ and a problem is showing up on the front end of the site when attempting to book an appointment. With the plugin configured to not require logging in, when I click on a time slot to select that appointment time the spinning progress icon appears but no further activity occurs.

With the plugin configured to require logging in on the front end, when I click on the login link a cancel button appears but no login fields.

I've tried deactivating all other plugins (though there weren't many others running) and switching between the Twenty Twelve and Twenty Eleven themes. These things don't help. I'm not seeing any javascript errors in Firefox for Mac (though there are various warnings about other things). It's a fresh Wordpress 3.5.2 installation with no tweaks and just the default themes installed.

The Appointments+ site is currently at

The host is GoDaddy.

Any assistance appreciated.

-Rob Galbraith