If you use the Windows XP's Hibernation feature on your laptop, you may want to delete the Hiberfil.sys file from the hard disk before defragmenting. When you put your computer in hibernation, Windows XP writes all memory content to the Hiberfil.sys file before shutting down the system. Then, when you turn your computer back on, the OS uses the Hiberfil.sys file to put everything back into memory, and the computer resumes where it left off. However, Windows XP leaves the Hiberfil.sys file on the hard disk, even though it's no longer needed.

The Hiberfil.sys file, which can be very large, is a special system file that Disk Defragmenter cannot defragment. Therefore, the presence of the Hiberfil.sys file will prevent Disk Defragmenter from performing a thorough defragmenting operation.

Follow these steps to remove the Hiberfil.sys file from the hard disk:

1. Access the Control Panel and double-click Power Options.
2. Select the Hibernate tab in the Power Options Properties dialog box.
3. Clear the Enable Hibernation check box and click OK.

As soon as you clear the check box, Windows XP automatically deletes the Hiberfil.sys file from the hard disk. Once you complete the defrag operation, you can re-enable the Hibernation feature.