127gb on 1tb hard drive, most hidden. What is it?

The computer has a one tb drive, checking properties in Windows Explorer says that 127gb space is currently in use. I used a freeware program "Disktective" to show the amount being used and what was using it. It also says that 127gb are in use, but only accounts for about a third of it. I ran Disk Cleanup with everything checked that could be a cause, but nothing changed. The computer runs fine, but this massive amount of unaccountable hard drive usage is alarming. Is this normal for Windows 7 and if so, can anybody tell me what's causing it? TIA.

John Corliss

Never mind. Once I posted that message, the forum came up with suggested related discussions. They all point towards shadowstorage recovery point backups. Or whatever they're called. I also deleted 121gb of pirated movies that my (late, he took his own life a couple of months ago but that's another story) neighbor had put on my desktop without telling me. I mean, come on. I have a Netflix account, why would I want that stuff anyway? Deleting that gob of garbage will definitely speed up AV scans and defragging. However, the 127gb used space figure I came up with was after I deleted that stuff. It was too large to go to the Recycle Bin (obviously), so it was permanently deleted. That's why I wondered why 127gb was still in use. Anyway, consider this question answered and thanks anyway.