The Microsoft Loopback adapter is a testing tool for a virtual network environment where network access is not available. Also, you must use the Loopback adapter if there are conflicts with a network adapter or with a network adapter driver. You can bind network clients, protocols, and other network configuration items to the Loopback adapter, and you can install the network adapter driver or network adapter later while retaining the network configuration information.
To manually install the Microsoft Loopback adapter in Windows XP, follow these steps:
1. Click Start--> and then click Control Panel.
2. If you are in Classic view--> click Switch to Category View under Control Panel in the left pane.
3. Double-click Printers and Other Hardware--> and then click Next.
4. Under See Also in the left pane--> click Add Hardware--> and then click Next.
hardware device--> and then click Next.
hardware that I manually select from a list--> and then click Next.
8. Click Network adapters--> and then click Next.
9. In the Manufacturer box--> click Microsoft.
10. In the Network Adapter box--> click Microsoft Loopback Adapter--> and then click Next.
11. Click Finish.