Microsoft has released an update to Windows Vista—current only available to Microsoft’s business customers and volume licensees—which shuts down so-called “frankenbuilds” of Windows Vista.

“Frankenbuilds” are unauthorized version of Windows Vista cobbled together from disparate software components&dmash;usually mixing together files from the Vista release with filed from pre-release test builds—in an effort to circumvent the operating system’s built-in product activation system. With the update, Vista can detect when its components have been tampered with, and will then go through a validation check to ensure the operating system is authentic. Users will be able to use the product for 30 days; if it’s not activated within that time, the operating system will shut down to a reduced functionality mode.

A post to Microsoft’s Windows Genuine Advantage Blog notes this is the first time Microsoft’s new under-the-hood antipiracy technologies rolled into Windows Vista are being used in the real world. Microsoft is also keen to point out that consumers should beware of counterfeit and pirated software, since the new technologies in Vista make it ever more likely the operating system will drop to reduced functionality after 30 days (although users would still be able to get to their files and data).