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.
After you install Windows Vista Service Pack 1 (SP1), existing system restore points may no longer be available. Additionally, shadow copies of files may have been removed as part of the service pack installation.
Note To view the shadow copies of a file, right-click the file, click Properties, and then click the Previous Versions tab.
This issue occurs when you install Service Pack 1 (SP1) for Windows Vista on a computer that is low on available disk space. When you try to install the service pack on a computer that is low on available disk space, the installation process frees disk space by removing any existing system restore points and by creating a single new system restore point.
To work around this issue, free additional disk space before you try to install Vista SP1. The more free space that is available when you install the service pack, the less likely it is that existing restore points and shadow copies of files will be deleted.
For more information about how to free disk space in Windows Vista, see Windows Vista Help and Support. To see Windows Vista Help and Support, follow these steps:
Click Start, and then click Help and Support.
In the Search Help box, type disk cleanup, and then press ENTER.
If available disk space on the computer causes existing system restore points to be removed during a Windows Update installation of the service pack, a new system restore point is created immediately before the service pack is installed.
This new system restore point captures the system state after any permanent prerequisite releases for the service pack are installed but before the service pack itself is installed. Therefore, you may be unable to restore the computer to the exact state the computer was in before you began installing the service pack.
For more information about Windows Vista Service Pack 1, click the following article number to view the article in the Microsoft Knowledge Base:
936330 Information about Windows Vista Service Pack 1