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Full user review
"Put simply it works but always backup before using."
After restart you notice a definite increase in speed. This product solved a shutdown problem I had by (I think) realigning all system files in sequence. I don't use it often but I do use it within a sequence of backups.
It takes time (overnight) and it needs to boot from an external drive (or CD/DVD) to fully defrag system files. Nothing new here though.