Please read this article before proceeding.

To disable IPv6 for Windows7 or Windows Vista:

1. Click Start, and typeregedit in the Start Search box.
2. Click regdit.exe in the Programs list.
3. In the User Account Control dialog box, click Continue.
4. In the Registry Editor, locate and then click the following registry subkey:
   
   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip6\Parameters\
   
   
5. Double-clickDisabledComponents to modify the DisabledComponents entry.
6. Type DisabledComponents | press ENTER. Please note: If the DisabledComponents entry is unavailable, you must create it. To do this, please follow this steps before proceeding to step 7:
   1. In the Edit menu, point to New then click DWORD (32-bit) Value.
   2. Type DisabledComponents | press ENTER.
   3. Double-click DisabledComponents.
7. Type any one of the following values to configure the IPv6 protocol, then click OK:
   1. Type 0 to enable all IPv6 components. Please note: The value “0” is the default setting.
   2. Type 0xffffffff to disable all IPv6 components, except the Ipv6 loopback interface. This value also configures Windows Vista to use Internet Protocol version 4 (IPv4) instead of IPv6 in prefix policies.
   3. Type 0x20 to use IPv4 instead of IPv6 in prefix policies.
   4. Type 0x10 to disable native IPv6 interfaces.
   5. Type 0x01 to disable all tunnel IPv6 interfaces.
   6. Type 0x11 to disable all IPv6 interfaces except for the IPv6 loopback interface.
8. Restart your computer.

Please note: Using a value other than 0x0 or 0x20 will cause the Routing and Remote Access service to fail after this change goes into effect.