You may always here from people in the industry that IPv6 “breaks things/stops things working” and that the recommendation is to disable it.
If you where to speak to Microsoft or attend their seminars, you will always hear them say DON’T disable IPv6. So who is correct!! The link below gives you an insight into IPv6. I’ve extracted an example Q and A from the list.
IPv6 for Microsoft Windows
Q. What are Microsoft’s recommendations about disabling IPv6?
It is unfortunate that some organizations disable IPv6 on their computers running Windows 7, Windows Vista, Windows Server 2008 R2, or Windows Server 2008, where it is installed and enabled by default. Many disable IPv6-based on the assumption that they are not running any applications or services that use it. Others might disable it because of a misperception that having both IPv4 and IPv6 enabled effectively doubles their DNS and Web traffic. This is not true.
From Microsoft’s perspective, IPv6 is a mandatory part of the Windows operating system and it is enabled and included in standard Windows service and application testing during the operating system development process. Because Windows was designed specifically with IPv6 present, Microsoft does not perform any testing to determine the effects of disabling IPv6. If IPv6 is disabled on Windows 7, Windows Vista, Windows Server 2008 R2, or Windows Server 2008, or later versions, some components will not function. Moreover, applications that you might not think are using IPv6—such as Remote Assistance, HomeGroup, DirectAccess, and Windows Mail—could be.
Therefore, Microsoft recommends that you leave IPv6 enabled, even if you do not have an IPv6-enabled network, either native or tunneled. By leaving IPv6 enabled, you do not disable IPv6-only applications and services (for example, HomeGroup in Windows 7 and DirectAccess in Windows 7 and Windows Server 2008 R2 are IPv6-only) and your hosts can take advantage of IPv6-enhanced connectivity.