Why can't my browser access http://127.0.0.1:35782/ when trying to add my computer to Ubuntu One?

You may receive the following error if you have a local firewall running on your machine and are trying to setup the Ubuntu One client by adding your computer to the service.

ERROR
The requested URL could not be retrieved
While trying to retrieve the URL: http://127.0.0.1:35782/

The solution is to set your browser to not use the firewall/proxy for localhost and 127.0.0.1. In Firefox, you can find this setting by going to: Preferences->Advanced->Network (tab) and make sure the "No Proxy for:" field is set to: localhost, 127.0.0.1