Defragment windows

I faced a problem with windows XP. It scanned my 'F' drive every time I start windows. I tried to run defragmenter and defragment the drive from the start menu. But it showed some warning that it is scheduled for some scan and degragmentation can not be done.
I managed for force defragment the drive through command prompt. If you want to defragment a drive you can try this method.

Start → Command → defrag X: (here X= desired drive)

If you want to analyze of force defragment, write “defrag /?” and hit enter. Then follow the instructions.