To disable certain IPv6 components yourself, follow these steps:

1. Click Start
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   , type regedit in the Start Search box, and then click regedit.exe in the Programs list.

2. In the User Account Control dialog box, click Continue.
3. In Registry Editor, locate and then click the following registry subkey:
   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip6\Parameters \
4. Double-click DisabledComponents to change the DisabledComponents entry.
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   Note If the DisabledComponents entry is unavailable, you must create it. To do this, follow these steps:

   1. In the Edit menu, point to New, and then click DWORD (32-bit) Value.
   2. Type DisabledComponents, and then press ENTER.
   3. Double-click DisabledComponents.
5. Type any one of the following values in the Value data field to configure the IPv6 protocol to the desired state, and then click OK:
   1. Type 0 to enable all IPv6 components. (Windows default setting)
   2. Type 0xffffffff to disable all IPv6 components except the IPv6 loopback interface. This value also configures Windows to prefer using IPv4 over IPv6 by changing entries in the prefix policy table. For more information, see Source and Destination Address Selection
      (http://technet.microsoft.com/library/bb877985.aspx)

      .

   3. Type 0x20 to prefer IPv4 over IPv6 by changing entries in the prefix policy table.
   4. Type 0x10 to disable IPv6 on all nontunnel interfaces (both LAN and Point-to-Point Protocol [PPP] interfaces).
   5. Type 0x01 to disable IPv6 on all tunnel interfaces. These include Intra-Site Automatic Tunnel Addressing Protocol (ISATAP), 6to4, and Teredo.
   6. Type 0x11 to disable all IPv6 interfaces except for the IPv6 loopback interface.

source: http://support.microsoft.com/kb/929852/en-us