Microsoft has silently upgrade Windows Vista (more specifically Windows Vista SP1) build version number from 6001.18000.080118-1840 to 6001.18063.080425-1930. The upgrade is done by the Update for Windows Vista KB952709 which was originally released on June 10, 2008, but almost immediately within days been taken off and retracted from Microsoft site.
It’s unknown if the KB 952709 is an intended official release, or just a accidental leaked test build which never plan to make public. What makes KB952709 more mysterious is the sudden retraction of the availability of KB952709 downloads (original link for x86 and x64 from Microsoft Download Center and its related Knowledge Base Article number 952709 from Microsoft Support, with no reason given.
Users who manage to download and install KB952709 update will see the following new build version number indicating 6001.18063 in the HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion registry key:
Microsoft pages about KB952709, before been taken down, summarized that KB952709 is a reliability update which resolves some performance and reliability issues in Windows Vista. By applying KB952709 update, user can achieve better performance and responsiveness in various scenarios.
The main attractiveness of the KB952709 is that it intends to fix long running Windows Vista issue – performance and sluggishness, similar to KB938979 update released prior to Service Pack 1. As the setup installation files has been taken off Microsoft Download Center, users who want to install KB952709 can download the unofficial hosted copies which manage to be downloaded by some users before Microsoft links are offline, using download links below. But note that as Microsoft has recalled the KB952709 release, so you take your own risk in downloading and installing the KB952709, although no users reported any problems after installing the update, nor the update actually helps to speed up Windows Vista significantly.
KB952709 for 32-bit Windows Vista x86:Windows6.0-KB952709-x86.msu
KB952709 for 64-bit Windows Vista x64: Windows6.0-KB952709-x64.msu
Update: Update for Windows Vista KB952709 has been officially released.