Support for Windows Vista Service Pack 1 (SP1) ends on July 12, 2011. To continue receiving security updates for Windows, make sure you're running Windows Vista with Service Pack 2 (SP2). For more information, refer to this Microsoft web page: Support is ending for some versions of Windows.
On a Windows Vista-based computer or on a Windows Server 2008-based computer, the Microsoft ISATAP adapter appears with a yellow exclamation mark (!) next to it in Device Manager. Additionally, when you open the properties dialog box for the device, you receive an error message that resembles the following:
Windows cannot load driver (Code 31)
You can safely ignore this error message. This error message does not indicate a problem with the adapter. The adapter will continue to work correctly.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
The Microsoft ISATAP device Inter Site Automatic Tunneling Address Protocol is used to help enterprises transition to an IPv6 infrastructure. The ISATAP adapter encapsulates IPv6 packets by using an IPv4 header. This functionality enables the client to transport IPv6 traffic over an IPv4 infrastructure. This approach lets organizations slowly migrate to an IPv6 infrastructure without having to spend excessive time and financial resources to convert to the new infrastructure.