Complex sentence: The tool PageDefrag could defragment Windows system files such as the swap file and the files that store the Windows registry by running at boot time before the GUI is loaded; since Windows Vista it is not fully supported and has not been updated.
Split into simpler sentences: The tool PageDefrag could defragment Windows system files such as the swap file and the files that store the Windows registry by running at boot time before the GUI is loaded. Since Windows Vista, the feature is not fully supported and has not been updated.