Defraggler has a Boot-Time Defrag option which allows you to defrag files that are normally locked by the Operating System before the operating system is fully loaded.
To enable Boot-Time defrag:
When you enable this option a dialog box will be displayed to inform you that this option has been switched on and ask you whether you would like to reboot your PC now. If you choose YES, your PC will be rebooted and defragged. If you choose NO, your PC will be defragged upon the next reboot.