Control panel Ubuntu One works only when I login as Admin. As a user the initial window will open. But not window will open if, I check on "I already have an account". Syncing files, contact and notes works fine. Only control panel does not.
As far as we know there is a bug in Ubuntu One regarding the installation process in machines that have Windows Vista or Windows 7.
The issue is as follows, when you install the application the system will ask you for elevated privileges and due to the bug the creation of the account will be related to the admin account that installed the application because the process uses such elevated privileges to create/link the account.
We have a bug fix for this and will be ready for the next release. In order to fix the issue with your installation you have to remove the credentials of Ubuntu One from the registry of the admin account.