View source for Reinstalling the TCP/IP stack on Windows XP

When viewing the list of components for a network interface, you may notice that the Uninstall button is disabled when Internet Protocol (TCP/IP) is selected. In Windows XP, the TCP/IP stack is considered a core component of the operating system; therefore, it is not possible to uninstall TCP/IP in Windows XP.

In extreme cases, reinstalling the Internet Protocol stack may be the most appropriate solution. With the NetShell utility, you can now reset the TCP/IP stack back to a pristine state, to the same state as when the operating system was installed.

The NetShell utility (netsh) is a command-line scripting interface for the configuring and monitoring of Windows XP networking. This tool provides an interactive network shell interface to the user.

In Windows XP, a reset command is available in the IP context of the NetShell utility. When this command is executed, it rewrites pertinent registry keys that are used by the Internet Protocol (TCP/IP) stack to achieve the same result as the removal and the reinstallation of the protocol.

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\ 

and

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\DHCP\Parameters\

Command Usage:<br />
<code>netsh int ip reset [ log_file_name]</code>

To successfully execute the command, you must specify a log file name where actions taken by netsh will be recorded. For example, typing either of the examples that are listed in the "Command Samples" section later in this article at a command prompt would reset the TCP/IP stack on a system and record the actions that were taken in the log file, Resetlog.txt. The first sample creates the log file in the current directory, while the second sample demonstrates the use of a path where the log will be created. In either case, where the specified log file already exists, the new log will be appended to the end of the existing file.

Command Samples:<br />
<code>netsh int ip reset resetlog.txt</code>

Source:
http://www.petri.co.il/reinstall_tcp_ip_on_windows_xp.htm