IPv6 for Windows

Unlike Windows XP and Windows Server 2003, IPv6 in Windows Vista and Windows Server 2008 cannot be uninstalled. However, you can disable IPv6 in Windows Vista and Windows Server 2008 by doing one of the following:

Add the following registry DisabledComponents value (DWORD type) set to 0xFF:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip6\Parameters

This method disables IPv6 on all your LAN interfaces, connections, and tunnel interfaces but does not disable the IPv6 loopback interface. You must restart the computer for this registry value to take effect.

Alternatively copy the contents below into a file using the reg extension and then run on your server.

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip6\Parameters]
"DisabledComponents"=dword:000000ff

NOTE:
If you disable IPv6, you will not be able to use Windows Meeting Space or any application that relies on the Windows Peer-to-Peer Networking platform or the Teredo transition technology.