We have domain.local in our datacenter. The DC is Server 2008. We have a Windows 2003 Server, Backup1.domain.local, that is used for network storage. We have created a domain account called "backupuser" for automation purposes. When we set a scheduled task to backup one of the servers in our domain, we set the task to run as domain\backupuser. When we set a scheduled task to backup a client's server, which is not in our domain, we create a local user on that server with the same name and password, and set the task to run as that local user. The scheduled tasks access the network storage server through UNC (i.e., \\backup1\d$\backup_directory). This has been working fine.
We recently added another network storage server, backup2. It is using Windows 2008 Server. This same system is working fine for any machine in our domain, but the local user strategy is now returning 0xc0000064 (user does not exist) during authentication. We cannot use a domain account to run the task since the local system is not aware of the domain and provides no local access for its accounts. How can we have a local user account still be able to access the network shares via UNC?