I, along with some other people, have lost a lot of free space to using Defraggler ( approx. 150 GB / 1 TB on D: and approx. 50 GB / 320 GB on C: ). While this is not a pressing problem for me, it is particularly annoying. I have attached a screenshot clearly showing just how much space is occupied by all the files on D: and how much free/used space is reported by Windows. I would also be quite happy to run more tests and attach debug logs. If anyone out there knows a fix for this, please let me know.