I am using a Nokia N72 as modem via bluetooth with my Ubuntu 12.10 laptop. It gets connected without any trouble, but after sometime a network disconnection notification is shown and the connection name disappears from the network manager notification icon. It happens very rapidly. Then i have to stop and restart Network-manager with the command: 'sudo stop network-manager' and 'sudo start network-manager'. Is there any way to get rid of this irritating process?