Tente alterar essas chaves de registro com o regedit:
HKLM\System\CCS\Services\LanmanWorkstation\Parameters
DWORD DomainCompatibilityMode = 1
DWORD DNSNameResolutionRequired = 0
HKLM\System\CCS\Services\Netlogon\Parameters
DWORD RequireSignOrSeal = 0
DWORD RequireStrongKey = 0