Defragmenter Doesn't Work In Windows Vista/7

In Windows Vista and above, opening the Defrag application from Explorer doesn't do anything. If running defrag from the command-line, the program displays its banner but otherwise doesn't do anything.

This may occur if defragsvc.dll is unregistered.

To resolve:

1. Click Start , type CMD in the search box and press Ctrl-Shift-Enter to invoke a command prompt in elevated mode:
   

2. Type:

   regsvr32 defragsvc.dll

   The system should display “DllRegisterServer in defragsvc.dll succeeded”.

3. Close the command prompt.