Solution:

1) Click the 'Start' button to display the 'Start' menu.
2) Select 'Programs' and select 'Accessories'.
3) Select the 'System Tools' menu and select 'Disk Defragmenter'.
'Disk Defragmenter' dialog box
4) Select the drive to be defragmented from the drop-down list box and click 'OK'. (A dialog box stating whether or not defragmentation is recommended for this disk appears.)
5) Do one of the following:

a) Click 'Start' to begin defragmentation immediately.
'Start' button
b) Select 'Advanced...' to specify whether the drive should be checked for errors or to specify a defragmentation method. (The 'Advanced Options' dialog box appears.)
'Advanced...' button
c) Select one of the following radio buttons from the 'Defragmentation' group:

1] Select 'Full defragmentation' (both files and free space) to consolidate both free space and space recovered from defragmented files. (This option will take longer.)
'Full defragmentation' radio button
2] Select 'Defragment files only' to defragment files without consolidating free space on the disk.
'Defragment files only' radio button
3] Select 'Consolidate free space only' to consolidate any free space on the disk (but without consolidating defragmented files).
'Consolidate free space only' radio button

d) Click 'OK'.

6) Click 'Start' to begin defragmentation.