When connecting to a share on a Windows Server 2003 server using the NET USE command for a DOS boot disk the following error occurs:

"Error 53: The computer name specified in the network path cannot be located"

The <LANROOT>\HOSTS and <LANROOT>\LMHOSTS entries must be present BEFORE loading the network client executables.

Functional DNS and WINS servers configured either statically or via DHCP should mitigate the need to configure these entries.

Disabling SMB Signing may also assist in resolving this issue.

You can disable SMB service signing in the following node of Default Domain Controllers policy on the domain controllers organizational unit:
Computer Configuration\Windows Settings\Security Settings\Local Policies\Security Options\Microsoft Network Server: Digitally sign communications (always)

Client, service, and program incompatibilities that may occur when you modify security settings and user rights assignments
http://support.microsoft.com/kb/823659