Ubuntu One Crashes On Login

[Glenn Stuart Morrissey]

glenn@acer:~$ lsb_release -rd
Description: Ubuntu 12.04 LTS
Release: 12.04
glenn@acer:~$

System Tools > Ubuntu One

Upon clicking the Ubuntu One Button on system tools the following error message appears:

'Sorry an error has occured and ubuntu one needs to close.'

Show details button ....

CredentialsError
DBusException(dbus.String(u'Traceback (most recent call last):\n File "/usr/lib/python2.7/dist-packages/dbus/service.py", line 707, in _message_cb\n retval = candidate_method(self, *args, **keywords)\n File "/usr/lib/python2.7/dist-packages/ubuntuone-client/ubuntuone/platform/credentials/linux.py", line 185, in find_credentials\n reply_handler=reply_handler, error_handler=error_handler)\n File "/usr/lib/python2.7/dist-packages/dbus/proxies.py", line 137, in __call__\n **keywords)\n File "/usr/lib/python2.7/dist-packages/dbus/connection.py", line 584, in call_async\n message.append(signature=signature, *args)\nValueError: Unable to guess signature from an empty dict\n'),)

Error message occurs every time I try to log on to Ubuntu One.