Hard Drive Disk Space Issue - Mysteriously Losing Space

For awhile now, my computer has had a strange problem of losing GBs worth of disk space on a daily basis. This even for some days when I don't download anything, or put any games on the computer, or anything like that.



I couldn't figure out what was causing it, so I started using a program named WinDirStat. The program is pretty good, and was helpful for awhile. It enabled me to find some old files that I thought were removed a long time ago but were still clogging up my hard drive.



However, I've recently ran into a problem that even WinDirStat doesn't seem to be able to help with. The "Unknown" files that I see coming up when I run WinDirStat just keeps getting bigger and bigger in disk space use. And unlike the other file types, WinDirStat does not seem to enable me to delete these.



So does anybody here know what these "Unknown" files might entail? Are they something that's necessary for the computer to run properly, or do they reflect something more worrisome that should be deleted? Is there a way to get rid of them and/or a way to determine what exactly they are?



Any help with any of this would be greatly appreciated.

Hard Drive Disk Space Issue - Mysteriously Losing Space