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Note: Before you run ScanDisk or Disk Defragmenting, run Ad-Aware and Spy-Bot. You can get these programs, for FREE, at our Download Center.

In order to keep your system running at peak performance, you have to do some periodic maintenance. Some basic maintenance practices, such as deleting unused files, removing unneeded programs, and empting the Recycle Bin, just don't cut it. Two other processes can also help save disk space and keep file access time to a minimum.

The ScanDisk utility that comes with Windows performs two essential functions: it locates lost clusters and locates and marks bad sectors on the disk.

Lost clusters are disk areas that used to be assigned to files. When the files were deleted, these clusters were not released by the operating system (for whatever reason). Programs with lost clusters can no longer function and have to be reinstalled. One common cause of lost clusters is shutting the computer down incorrectly. When you shut your computer down, Windows deletes unnecessary temporary files. If you shut the computer down, some of these files aren’t deleted and others are in the process of being deleted, causing lost clusters.

ScanDisk can also locate bad sectors. Bad sectors are actual flaws in the surface of the disk. These areas of the disk can not store information reliably, so Windows marks them as unusable. Until they are marked, there is the potential that Windows will try to store data on those sectors. This will either cause data to be lost or, will cause the program trying to do the writing to crash, losing the data before it’s stored. Once marked, Windows avoids bad sectors when saving files.

Caution: Bad sectors tend to spread. If you find bad sectors on a floppy disk, throw it away. The cost of a floppy is not worth the hassle of trying to fix the errors. If the bad sector is on a hard drive, use caution, back up your data frequently, in case the bad sector spreads, causing you potential data loss. Consider replacing the hard drive as soon as possible.

To perform a ScanDisk:

Access the ScanDisk Program:

>> Start menu, Programs, Accessories, System Tools, ScanDisk

>> Right-click on the drive's icon, Properties, Tools, click the Check Now button

	Select the drive to scan (you can scan floppies too)
	Select Standard to check for lost clusters only or Thorough to check for both lost clusters and bad sectors (Thorough requires considerably more time because test data is read and written to each sector to test it.)
	Check the Automatically fix errors option to have ScanDisk fix any errors it finds (lost clusters) without help from you. You should leave this option OFF to see the number of lost clusters that were found.
	Instruct ScanDisk on what to do with lost clusters. ScanDisk allows you to save the contents of lost clusters in case you have ambitions of trying to reconstruct the broken files.
	Click the Start button (in the dialog box) to begin the ScanDisk process, then sit back and watch (if you want).

As you add and delete files from a disk, Windows in its efforts to efficiently use disk space, fragments files. When you delete a file, Windows makes the space available for new files. When you add a new file to the disk, Windows attempts to store it as close to the beginning of the disk as possible. If the entire file doesn’t fit in the first available cluster, the part that does fit is placed there along with a link to the remainder of the file. This process continues until the entire file is saved. Most personal files (letters, spreadsheets, databases, etc.) fit in one cluster, so this is not a big problem. But programs, and graphics files can easily fill many clusters. Files split over many clusters are referred to as fragmented. Fragmented files are inefficient to retrieve off the disk, the chain of file fragments must be followed until the file is complete. This is even more inefficient if programs are stored in fragments. Defragmenting moves file fragments, rearranging them until no files are fragmented, all file clusters are right next to each other. If you have a large hard drive to defragment, this can be a long process. Start defragmenting just before you go to bed. It should be done by the time you get up in the morning.

Before Disk Defragmenter, run ScanDisk. Disk Defragmenter can not defragment a disk with lost clusters. The lost clusters have to be cleaned up first.

Disk defragmenting of a hard drive can take time. Turn off your screensaver or the disk defragmenting may never finish. Even screensavers create temporary files. Disk defragmenter senses these new files and starts all over again. The subsequent times are much quicker, but the process starts over again every time the screen saver kicks in. Turning the screen saver off solves this problem. If you don’t want to turn the screen saver off, there is another option. If you open the Start menu (don’t select anything from it), the screen saver will not activate. Start the Defragmenter, then open the Start menu. The Disk Defragmenter should finish without interruption. If you still cannot defrag your hard drive, try running defrag in safe mode. To get into safe mode, reboot your computer. When it is booting up, repeatedly tap the F8 key. Eventually, you should get a little boot menu. Select the safe mode option. Once booted up, you can use the same steps listed above to defragment the hard drive.