I have a number of 877 routers used for ADSL backup, intermittently the ATM interface hangs cannot access the internet at all, the only way to start the ATM again is to do a "Clear int atm0" command

the Versions of IOS running are ADVSECURITY 124-4.T3, 124-6.T6 , and 124-6.T7

relevenent part of config below

interface ATM0

no ip address

no atm ilmi-keepalive

pvc 8/35

encapsulation aal5mux ppp dialer

dialer pool-member 1

!

dsl operating-mode auto

no shut

!

interface Dialer1

bandwidth 256

ip address negotiated

ip access-group 130 in

ip nat outside

ip virtual-reassembly

encapsulation ppp

dialer pool 1

dialer-group 1

no keepalive

no cdp enable

ppp authentication chap callin

ppp chap hostname xxxxxxx

ppp chap password yyyyyy

crypto map IPSec-VPN1

I have tried to see what is happening with debugs, but don't seem to be able to capture anything relevent

please advise.