Chkdsk (an acronym for check disk) is a Microsoft® utility designed to check the integrity of the data on a computer's hard disk drive as well as find and fix errors which could muddle data. On computers using Windows® XP and 2000, chkdsk is essentially a replacement for scandisk which was used on Windows® '95, '98 and ME versions. Running chkdsk on computers with Windows Vista or  Windows 7 is somewhat different, but provides the same benefits.

Running chkdsk on your Windows® XP or 2000 system can most often repair numerous minor Windows® problems you may have experienced and/or encountered. Many people regularly run chkdsk as a part of their overall computer maintenance plan.

Chkdsk harkens back to the days of MS-DOS and one can only wonder exactly why Microsoft® chose to revert to its use because it is, quite frankly, a little clunky, however, well worth the time and effort. There are several different methods that can be used to run chkdsk on a Windows® XP or 2000 machine but the most basic is as follows:

1. Click the Start button then select Run
2. In the Run window's Open box, type cmd or command
3. Click OK and an MS-DOS-style black screen will appear in a new window
4. Run chkdsk by typing one of the the following commands where the cursor is blinking:
a. chkdsk c: /f /r  and then press <Enter> (see Notes below)
OR
b. chkdsk c: /f  and then press <Enter> (see Notes below)
5. With either command, a message will appear that says:"chkdsk cannot run because the volume is in use by another process. Would you like to schedule this volume to be checked the next time the system restarts? <y/n>"
6. Type y (for "yes") and then press <Enter> Caution: canceling an already scheduled chkdsk is a giant hassle so be sure you want to run chkdsk before completing this step. For information about how to cancel an already scheduled chkdsk, visit Microsoft® at: http://support.microsoft.com/kb/158675
7. A message will appear that will say: "This volume will be checked the next time the system restarts"
8. Type exit and then press <Enter> to close the MS-DOS-style black screen window
9. Reboot (restart) the computer as you normally would and chkdsk will automatically begin running after your reboot (restart). While chkdsk is running, you will see a light blue window with a dark blue band at the top and bottom. Chkdsk will display the specific stage it is checking as well as the percentage of completion of the stage. You cannot do anything else on your computer while chkdsk is running. When chkdsk is finished, it will automatically reboot (restart) your computer.

For more information about chkdsk, visit the Microsoft® site at: http://www.microsoft.com/resources/documentation/windows/xp/all/proddocs/en-us/chkdsk.mspx

Notes:
Typing chkdsk c: /f (as in 4b above) will only fix errors that are encountered, while typing chkdsk c: /f /r (as in 4a above) will both fix errors and recover lost data. Running chkdsk with both the /f and /r options (as in 4a above) can often take a considerable amount of time—depending upon the size of your hard drive and the amount of data stored on it. For example, a 60GB hard drive with half the drive filled with data will take about an hour and fifteeen minutes when you use both the /f  and /r options. Be prepared to take a long lunch because waiting for chkdsk to finish is somewhat akin to watching paint dry.

While running chkdsk with only the /f option (as in 4b above) is faster, it will only fix errors, not recover any lost data. However, using only the /f option on a similar 60GB hard drive with half the drive filled with data will only take about twenty minutes.