I've got the latest versions of wordpress and Subscribe2. I've created a page with the S2 token. I've told the widget and the Subscribe2 settings under Appearance to use this page. I'm sending emails from an email address associated with my domain name. Confirmation emails are being sent, but when the user clicks the confirm link, they are taken to a "page not found" error message and are not confirmed.
I have disabled all my plugins except Subscribe2, though I'm not using any SEO plugins because this is a personal website.
This was working a couple of days ago, and I'm not sure what I might have changed that has now broken the Subscribe2 functionality. Any ideas?