Elmar, Is your router being used for internet access and what sort of connection are you using? If your using ADSL then you will have to reenable it. Administratively down means that it has been manually shut down or because of a password recovery.. ATM0 is binded to the dialer interface and the virtual-access interfaces on DSL setups. Not sure if this will work as I do not have any test routers to try this on but maybe "no interface ATM 0" might do it but somehow I doubt it.
Rob