Q When running Disk Defragmenter, there were still five files marked red as fragmented after it had finished.

I tried to run it again but this did not affect these files. Since then, I keep getting warnings to defragment the hard disk.
Mr J Singleton

A Files are saved to a hard disk in a number of ‘slots’; if a given file is bigger than the number of continuous available slots, then the file is saved in multiple parts of the disk, thus ‘fragmenting’ the file.

There are several reasons files do not properly defragment. The most common is that there is not enough empty space on the hard disk for the finished file. This may even apply if there is plenty of space remaining but the fragmented files are very big; there is not enough space to assemble the file in one piece.

Some extra software, such as Diskeeper, can cope better with this, but they are not free.

Some files will always be fragmented due to the way Windows operates, and while it should be kept to a minimum, there are times when it is not a serious problem. It is not worth defragmenting a large video file that is only rarely watched, for example.

To see the files that are causing the problems, click on the Analyze button in the Disk Defragmenter window and then on Report. This will display a list of all the fragmented files, including how big the file is and how many fragments it is in. Even a few tens of fragments should not affect the performance of the computer so long as there are not too many files in this state.

Before running the Disk Defragmenter utility, make sure any unwanted files are deleted to make as much room available as possible. Left-click on My Computer, then right-click on Local Disk (C:) and select Properties from the menu that appears. Left-click on the Disk Cleanup button. This utility will examine the hard disk for files that can be safely deleted.

When it has finished, it will show the different areas where space can be saved. We recommend leaving the Office Setup Files option unchecked but the rest can be checked.

The compress old files option can save a lot of space but can take some time. Click on OK when you are happy with the selections and confirm the decision by clicking on Yes in the message window. The files will then be compressed or deleted.