By default the Enterprise Server's 'Default Computer Policy' (or any custom created configuration policy) will not be applied on the Enterprise Server itself.
All Windows platforms that support the Enterprise Server
Configuration Policies can be applied only if a DSM Agent is present on a machine and since there is no Agent present on the Enterprise server any configuration policy change will not be applied on the Enterprise Server.
Install a DSM Agent on the Enterprise Server pointing to a Domain Manager of your choice (with 'CAF SETSERVERADDRESS <domain manager>').
Once the DSM Agent is installed, the Enterprise Server will show up under 'All Computers' on the Domain Manager.
Create a new policy on the Domain Manager with the desired policy settings and distribute the policy to the Enterprise Manager unit listed under 'All Computers'.