User Account Control
By default, Windows Vista and later use User Account Control (UAC) to enforce security. One of UAC's features denies administrative rights to a user who accesses network shares on the local computer over a network, unless the accessing user is registered on a Windows domain or using the built in Administrator account. If not in a Windows domain it is possible to allow administrative share access to all accounts with administrative permissions by adding the LocalAccountTokenFilterPolicy value to the registry.