When defrag doesn't help

I often get asked if having too many files on a hard drive can cause a computer to slow down.

This is a loaded question because the answer depends on many variables. Usually, having lots of files on your drive does not cause problems if the drive is big enough. But if you have millions of tiny files, searches, defragmentation and other tasks may take longer than if you have a smaller number of larger files.

People assume that defragging and running the drive cleanup utility will speed up their machine. If you have tried this, you probably know it doesn't work; often running these tools has no apparent effect.

Most of us have modern computers with mammoth hard drives, meaning we can continue to store our music, photos and movies without worrying that things are getting cramped on the drive. My rule of thumb is that if your drive is over half full, your computer's performance will begin to decline and with drive prices so low, upgrading to a bigger model should be considered.

Any slowing down won't be that obvious, but the more your drive fills the slower things will become because of drive physics and other limitations.

You can view your drive space by opening My Computer and right- clicking on the hard drive you want to check. From the resulting menu, choose Properties and you will be presented with a pie chart indication of used and free space. The free space listed there is a general figure only; bear in mind Windows uses a fair chunk of drive space for its own purposes and if you try to impinge on that, bad things will happen.

To really clean up, you need to view all files and folders on your computer. Unhide files by opening Explorer, go to Tools, Folder Options, View and check Show Hidden Files and Folders and uncheck Hide Protected Operating System Files.

You should now see system files in the "root" of your system drive and your user profile folders. These files are hidden for a reason and you should be very careful with them.

Check C drive; you should have pagefile.sys and perhaps hiberfil.sys. These files are usually quite large and though you can try deleting them, Windows won't let you because they are in use. If your drive gets so full that these files can't be properly created and managed, problems will arise.

Before that happens though, you should receive Low Disk Space warnings. This dialogue also links to the disk cleanup utility, which finds temporary files and folders that can be safely deleted. Those of you who are more confident can trawl the hard drive and delete files you know are safe to delete, but be very careful because some files and folders, even 0-byte files which apparently contain nothing, are required by Windows (or other programmes) and they will break if deleted.

For example, there is a file called ntldr in the root of C drive; Windows will let you delete it, but next time you try to boot you will get no further than a message stating " ntldr missing".

Just because Windows allows you to delete something doesn't mean it is safe to delete.

Utilities such as ATF Cleaner, CCLeaner and others are useful in cleaning out commonly used temp folders but don't go as deep as they should for safety reasons. Going through manually is the only real way to ensure all the junk is gone, which is why utilities will never replace an experienced tech who knows what they are doing.

- © Fairfax NZ News