Volume %1!s! has %2!d!% free space, but <1% is available for use by Disk Defragmenter (due to reserved system space). To ...

Volume %1!s! has %2!d!%% free space, but <1%% is available for use by Disk Defragmenter (due to reserved system space).  To run effectively, Disk Defragmenter requires at least %3!d!%% usable free space.  There is not enough disk space to properly complete the operation.  Delete some unneeded files on your hard disk, and then try again.