I just migrated Drupal from my development site to my production site. This included a full database migration as well as a file migration.
Now, after adding products to my shopping cart and then clicking the checkout button all that happens is that the shopping cart refreshes. This happens whether or not I'm logged in.
I had a very similar problem with Ubercart in my site as well. The difference is that I would end up getting told that there was an infinite redirect and that seem to be quite what you're hitting. However, the root cause might be the same. I had an error in an email template that was supposed to get sent after completing checkout. I would suggest checking your server logs and possibly even setting display_errors = On in your PHP config. Also check your Watchdog logs for any errors.
