Ubuntu One freezes on Sign in

[Tobia Fasciati]

When I start for the first time ubuntuone-installer and I click "Sign me in with existing account", the window freezes (everything becomes grey).

What I get in the terminal:
tobia@smeagol:/etc$ ubuntuone-installer
tobia@smeagol:/etc$ QGtkStyle was unable to detect the current GTK+ theme.
Unhandled error in Deferred:
Unhandled Error
Traceback (most recent call last):
Failure: ubuntuone.platform.credentials.CredentialsError: dbus.Dictionary({dbus.String(u'errtype'): dbus.String(u'CredentialsError')}, signature=dbus.Signature('ss'))

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: ubuntuone-installer 2.99.90-0ubuntu1
ProcVersionSignature: Ubuntu 3.2.0-18.29-generic 3.2.9
Uname: Linux 3.2.0-18-generic x86_64
ApportVersion: 1.94.1-0ubuntu2
Architecture: amd64
Date: Sat Mar 10 19:10:12 2012
InstallationMedia: Lubuntu 12.04 "Precise Pangolin" - Alpha amd64 (20120309)
PackageArchitecture: all
ProcEnviron:
 TERM=xterm
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: ubuntuone-installer
UpgradeStatus: No upgrade log present (probably fresh install)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.