The supplied defragmentor may require up to 1/2 the drive empty to defrag all but a few files. This is by design. It's not broken and what's left is unlikely to cause any issue.
i have run the defragmentation program several times and it completed several times but it never completely defrags my hard drive after it finished defragging every time i pressed analyze and it still said you should defragment this volume and the fragmentation stays at 14%!
i am running windows xp professional and i have over 15% free disk space when running it
anything i'm doing wrong?