Create user 1 and... nothing happens?

Hi folks,

Well, I just set up a brand new server and installed the 4.7.0 final code on it, thinking it would be more stable than the current CVS (?). Anyway, I click "create your first account" and am taken to: http://example.mysite.com/?q=user/register

I am taken to that page, I type in "IT" as the first user, "it@example.com" as the email, click Submit, and... nothing happens.

the page clears both fields, no email is sent, the page URL stays exactly where it was, and no user record is generated in the MySQL Users table. It doesn't go to the "you are logged in" page and I don't know the password, so I'm quite stuck.

Help?

Thanks, John @ TurboChef