How can I install the Microsoft Loopback adapter in Windows XP?

Start the Add Hardware Control Panel applet (go to Start, Control Panel, Add Hardware).

Click Next to go to the introduction dialog box.

Select "Yes, I have already connected the hardware," then click Next.

Scroll to the bottom of the list of hardware, select "Add a new hardware device," then click Next.

Select "Install the hardware that I manually select from a list (Advanced)," then click Next.

Select "Network adapters," then click Next.

Select Microsoft as the manufacturer, select "Microsoft Loopback Adapter" as the adapter, then click Next.
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Click Next to go to the confirmation page.

Click Finish to complete the installation.