After replicating VM from ESX 3.5 to ESX 4.x you may see the following error from a replicated Windows operating system: "The IP address XXX.XXX.XXX.XXX you have entered for this network adapter is already assigned to another adapter Name of adapter."
The Replica's virtual hardware will be at the latest HW version available on ESX host. Therefore VMware virtual network adapters will be upgraded as well, leaving old network adapter with the same IP address in the Windows registry, but hidden in the Device Manager (My Computer > Properties > Hardware > Device Manager). This hidden adapter is called a ghosted network adapter.
Using the Show Hidden Devices option in the Device Manager (View > Show hidden devices) does not always show the old virtual NIC (ghosted adapter) to which that IP Address is assigned.
To resolve this issue, make the ghosted network adapter visible in the Device Manager and uninstall the ghosted network adapter from the registry: