Hello !
After upgrading to version 1.18.185 Defraggler writes into the area that is reserved for the MFT.
To verify that this behavior is new, I reinstalled version 1.17.172.
After that, Defraggler works as expected again, i.e. the reserved MFT space gets not overwritten any more.
Operating system: Windows XP, SP3
File system: NTFS
Besides that bug (is it any?), it's a cool tool !
Thanks.