Unlike RAM, your hard disk has moving parts, and as such is susceptible to errors. Over time, clusters can become corrupted, part of files can become lost, and a range of other errors can occur. You may have noticed how Windows 98/ME will run Scandisk when you don’t perform a proper shutdown, or how Windows 2000/XP will run Chkdsk in the same situation. In almost all cases, users choose to skip these checks, mainly because they can be somewhat time consuming, especially on large partitions. The truth is that you really should take the time to run both at least occasionally, especially if your system is getting old – it may save you from a whole lot of lost data in the long run.
In general, you should run Scandisk or Chkdsk at least once per month on older systems. ScanDisk is found in the System Tools program group, while Chkdsk can be launched from the Run command by typing chkdsk.exe on Windows XP systems. If you do run ScanDisk on a Windows 98/ME system, be sure to use the “thorough” option, as this will scan the surface of the disk for any errors. It can take a while to complete, so consider running it when you’ve got something else to attend to.