Microsoft is warning customers that tools for blocking automatic upgrades to the newest service packs of Windows Vista and Windows XP will expire in the coming months.
In a note on a company blog aimed at enterprise IT professionals, Microsoft said the Vista Service Pack 1 (SP1) blocking tool expires on April 28, while the one for XP SP3 expires May 19.
The tools, which were released in December 2007, prevent service packs from reaching PCs via Windows Update, Microsoft's default update service, and are primarily used by corporations that have not yet tested or approved the newest upgrades.
Microsoft's policy is to let users block service packs for up to 12 months after general availability. That, however, doesn't necessarily mean users can block upgrades for a full year after the company has flipped the switch on automatic downloads.
The April 28 expiration date for the Vista SP1 blocking tool, for example, is almost exactly a year after April 23, 2008, when Microsoft triggered automatic upgrades. But it will give Windows XP users just over 10 months of blocking when it kills that operating system's tool in May; Microsoft began automatically upgrading Windows XP to SP3 in early July 2008.
The blocking tools, which are still available on Microsoft's site for downloading, are composed of an executable, a script and a group policy template.
Microsoft regularly issues such tools when it rolls out major updates to its operating system software and to its Internet Explorer (IE) browser. Earlier this month, for instance, it posted a tool to bar IE8, which just launched in release candidate form, from PCs.
The Vista/XP toolkit that is available now will continue to block Vista SP2 installations for approximately a year after that service pack is released. According to recent reports, Vista SP2 is expected in final form sometime before mid-May.