I suggest to open a case with support

the CFS write error messages you are seeing are about quota being exceeded and dont have anything to do with you not being able to map the share

the server_export output is nice, but it's listing NFS shares and not CIFS shares

most probably you either have a name resolution problem on your Windows client or your credentials arent working.

trying nbtstat, net view and a manual map share as a drive letter should help isolating the problem

I suspect you have some issues with DNS and AD. The following two log entries confirm that - I am sure you are having more entries like these in the server log -

2007-11-19 21:22:26: LIB: 3: DNS update ERROR: Operation refused for policy or
security reasons while registering zsg03nas01.ds.mot.com
2007-11-19 21:39:30: SMB: 4: No DC available for site "ZSG14-Subnets-Hub" of do
main "mot.com", use out of site's DCs

Was there any recent update or patch applied on the AD side?

I suspect the Kerberos Realm issue as well - your AD domain is mot.com but the CIFS server is under ds.mot.com - which may be the DNS domain. This is an example of disjoint DNS - can be fixed by adding disjoint DNS entries with the CIFS servers.

I hope yo have already opened a case with NAS support as suggested by Rainer - if not please do so.

Thanks,
Sandip