After installing it at home without any problem, I'm trying to install Ubuntu One at work (Ubuntu 12.04, must use proxy). Apparently it can not connect to the server: I can't sign in of course, can't use the "forgotten password" form either (address not recognized), and if I open the dialog to create an account I get a message "There was a problem downloading the captcha, reloading...".
I tried installing
Ubuntu One behind a proxy, how to make it work?
and resinstalling the certificates: https://one.ubuntu.com/help/faq/why-am-i-getting-an-the-authentication-failed-error-on-windows-225/
... without any success.
What am I doing wrong?