Many of our readers are familiar with how dual-booting Windows Vista and Windows XP can cause restore points to be deleted by Windows XP (see our recent blog post for details). What you might not know is that some third-party tools can also cause the deletion of restore points by Windows Vista. If the third-party tool runs at boot time without running in Windows Preinstallation Environment (PE) or some version of Windows Vista, any changes that the tool makes to the disk will cause Windows Vista, once started, to invalidate and thus delete the restore points. Why are the restore points deleted? Because if a tool makes a change to the volume without going through Volsnap.sys (the volume shadow copy driver), when Windows Vista is started, it detects that it doesn’t have an accurate representation of the changes to the volume and thus can’t accurately reconstitute older versions of the file for System Restore (or any other application). This issue doesn’t affect Windows XP because the restore points are actually backup copies of system files stored under the Windows folder. As long as the third-party tool doesn’t change those files, the restore points in Windows XP remain intact.
To avoid having restore points deleted in Windows Vista, use third-party tools that run in Windows Vista or a version of Windows PE or Windows Recovery Environment (RE) that is based on Windows Vista.
–Jill and Dan Stevenson