got this on U1 client install mee too.
This is my syslog while this appened. tks

Feb 24 19:20:30 whale AptDaemon: INFO: Initializing daemon
Feb 24 19:20:31 whale AptDaemon.PackageKit: INFO: Initializing PackageKit compat layer
Feb 24 19:20:31 whale dbus[884]: [system] Successfully activated service 'org.freedesktop.PackageKit'
Feb 24 19:20:31 whale AptDaemon.PackageKit: INFO: Initializing PackageKit transaction
Feb 24 19:20:31 whale AptDaemon.Worker: INFO: Simulating trans: /org/debian/apt/transaction/780f8b9e3dbf4349a98102a823d51270
Feb 24 19:20:31 whale AptDaemon.Worker: INFO: Processing transaction /org/debian/apt/transaction/780f8b9e3dbf4349a98102a823d51270
Feb 24 19:20:36 whale AptDaemon.PackageKit: INFO: Get updates()
Feb 24 19:20:38 whale AptDaemon.Worker: INFO: Finished transaction /org/debian/apt/transaction/780f8b9e3dbf4349a98102a823d51270
Feb 24 19:21:05 whale AptDaemon: INFO: UpdateCachePartially() was called
Feb 24 19:21:05 whale AptDaemon.Trans: INFO: Queuing transaction /org/debian/apt/transaction/ac402d549a7c49baaa4594a758dc86f4
Feb 24 19:21:05 whale AptDaemon.Worker: INFO: Simulating trans: /org/debian/apt/transaction/ac402d549a7c49baaa4594a758dc86f4
Feb 24 19:21:05 whale AptDaemon.Worker: INFO: Processing transaction /org/debian/apt/transaction/ac402d549a7c49baaa4594a758dc86f4
Feb 24 19:21:06 whale AptDaemon.Worker: INFO: Updating cache
Feb 24 19:21:06 whale AptDaemon.Worker: INFO: Finished transaction /org/debian/apt/transaction/ac402d549a7c49baaa4594a758dc86f4
Feb 24 19:21:06 whale <U+FEFF>AptDaemon: INFO: InstallPackages() was called: dbus.Array([dbus.String(u'rhythmbox-ubuntuone'), dbus.String(u'ubuntuone-client-gnome'), dbus.String(u'ubuntuone-control-panel-qt')], signature=dbus.Signature('s'))
Feb 24 19:21:06 whale AptDaemon.Trans: INFO: Queuing transaction /org/debian/apt/transaction/220a5f8792cc4ba2bdc74fcf2d8a9f86
Feb 24 19:21:09 whale AptDaemon.Worker: INFO: Simulating trans: /org/debian/apt/transaction/220a5f8792cc4ba2bdc74fcf2d8a9f86
Feb 24 19:21:09 whale AptDaemon.Worker: INFO: Processing transaction /org/debian/apt/transaction/220a5f8792cc4ba2bdc74fcf2d8a9f86
Feb 24 19:21:10 whale <U+FEFF>AptDaemon.Worker: INFO: Committing packages: dbus.Array([dbus.String(u'rhythmbox-ubuntuone'), dbus.String(u'ubuntuone-client-gnome'), dbus.String(u'ubuntuone-control-panel-qt')], signature=dbus.Signature('s')), dbus.Array([], signature=dbus.Signature('s')), dbus.Array([], signature=dbus.Signature('s')), dbus.Array([], signature=dbus.Signature('s')), dbus.Array([], signature=dbus.Signature('s')), dbus.Array([], signature=dbus.Signature('s'))
Feb 24 19:21:10 whale <U+FEFF>AptDaemon.Worker: INFO: Committing packages: dbus.Array([dbus.String(u'rhythmbox-ubuntuone'), dbus.String(u'ubuntuone-client-gnome'), dbus.String(u'ubuntuone-control-panel-qt')], signature=dbus.Signature('s')), dbus.Array([], signature=dbus.Signature('s')), dbus.Array([], signature=dbus.Signature('s')), dbus.Array([], signature=dbus.Signature('s')), dbus.Array([], signature=dbus.Signature('s')), dbus.Array([], signature=dbus.Signature('s'))
Feb 24 19:21:10 whale AptDaemon.Worker: INFO: Finished transaction /org/debian/apt/transaction/220a5f8792cc4ba2bdc74fcf2d8a9f86
Feb 24 19:21:12 whale AptDaemon.PackageKit: INFO: Initializing PackageKit transaction
Feb 24 19:21:12 whale AptDaemon.Worker: INFO: Simulating trans: /org/debian/apt/transaction/857ca121167f4acab9c0e693c362ca70
Feb 24 19:21:12 whale AptDaemon.Worker: INFO: Processing transaction /org/debian/apt/transaction/857ca121167f4acab9c0e693c362ca70
Feb 24 19:21:12 whale AptDaemon.PackageKit: INFO: Get updates()
Feb 24 19:21:13 whale AptDaemon.Worker: INFO: Finished transaction /org/debian/apt/transaction/857ca121167f4acab9c0e693c362ca70
Feb 24 19:24:07 whale AptDaemon: INFO: Initializing daemon
Feb 24 19:24:07 whale AptDaemon: CRITICAL: Another daemon is already running