What to do when Amazon.com won't accept “Continue”

I am at the "Select Shipping Options" but no matter what I click, it just repaints the page.

The options are: "We're giving you a free 6-month trial of Prime Student", and the usual "free shipping", or "next friday", or "next tuesday" for various prices.

I tried relogging in. I tried returning to the home page. Still can't get to the "place order" page.

Suggestions?