Oh, I forgot to say that what I just said above assumes that the domain name in the Catalog is really in the DNS form (i.e. that it's really "domain.local"). Because normally, it's in the NetBIOS form (without the dot in it - e.g. "DOMAIN").
Please check one of the machines in the Computer Catalog (in the ADNM console) what domain name it shows, and use this domain name in the account spefication in the deployment task properties.
E.g. if the domain name is shown as DOMAIN, use
Domain: DOMAIN
Username: DOMAIN\Administrator
Password: <the domain admin password>
Hope this helps,
Vlk