Server Shuts Down

[carnold]

Since the update from 5.18 to 6 OSS Zimbra, our server shuts down once a day. I don't know if this is zimbra related but i thought i would post on the zimbra forums 1 since the uopdate this happens and 2 because of the following message log:
Sep 6 16:31:30 xx /usr/sbin/namcd[11751]: ldap_initconn: LDAP bind failed (error = [81]), trying to connect to alternative LDAP server
Sep 6 16:31:30 xx /usr/sbin/namcd[11751]: Unknown error returned reading configuration parameter: alternative-ldap-server-list
Sep 6 16:31:34 xx /usr/sbin/namcd[11751]: ldap_initconn: LDAP bind failed (error = [81]), trying to connect to alternative LDAP server
Sep 6 17:26:25 xx syslog-ng[2396]: syslog-ng version 1.6.8 starting

You can see that the server shut down during the zimbra LDAP error and the last line is the start up message. Anybody else experiencing this or can tell us about the LDAP error?
As i edit this i see that this may not even be zimbra related. We have Novell NDS also running on this server (zimbra bound to 1 ip and NDS bound to a different IP). Gonna stop the NDS service and see if the shut down happens......

[uxbod]

Are you using internal or external authentication ?

[carnold]

Using external auth, AD, but users aren't having any problems logging in.