If you have less than 15% free disk space, then Windows XP will not allow the defragmentation of your hard drive.
- But you can bypass this limitation, here's how:
- Start > Run > type "cmd" and press Enter
- In the command prompt type defrag x:-f and press Enter key.
- Defragmentation shall begin.
- Note that : replace x by the letter corresponding to the hard drive/ partition you want to defrag.