Tente criar um valor de registro DWORD em HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
chamado GpNetworkStartTimeoutPolicyValue
e defina-o como (decimal) 60:
(Se você estiver executando o XP SP2 ou posterior, você já tem o hotfix)
This problem may occur if the Group Policy engine or Active Directory times out while it waits for the network to start. A race condition may occur between the TCP/IP protocol and the network adaptor driver when they try to register with the Microsoft Network Driver Interface Specification (NDIS). If the TCP/IP protocol registers with NDIS before the network adaptor driver, for a short time it prompts higher user mode networking components that network connectivity is not available. During this short time, the Group Policy startup script cannot be downloaded.
This problem is more likely to occur on fast networks that use 1-gigabit network adaptors or in teaming environments where the network takes several additional cycles to negotiate link speed.