defragment black grid squares remain

[shokan]

After several defragmenting sessions, seven contiguous grid squares remain black. What is this?
Thanks.

[BertImmenschuh]

Just for general information, there's a number of 'squares' or files/file fragments that simply cannot be moved. It has to do with Windows needing them where put during installation and also by some programs. Don't worry about it. Win2000, WinXP and WinVista do not visually defrag as completely as programs for DOS could such as the built-in applet in MS-DOS 6.2x.