I just updated 12.04 and UbuntuOne crashed on login to the desktop and brought me here. This is regression, U1 has been working fine on precise so far. Also cannot log in to U1 client: red writing on the client states: "There was a problem while retrieving the crede" and then cuts off. Unable run u1sdtool to stop and start the daemon. Going to log a separate bug about that issue.
So U1 is completely dead