What everybody else has suggested, first, A/V, diskcheck, etc.
Then, 20G/day is a lot of file space.
Do you know what type(s) of file(s) are being created for that 20G? The file type might be a major clue as to which program or Win service is doing this. (file type= the file extension, the part of a filename after the dot, usually just three letters/numbers. Each file extension is 'registered'/assigned, to one or more programs or services that create/manipulate them.
That said, I have used an extremely useful little program called "
SequoiaView" for decades. It presents you with a very neat and detailed graphical display of the contents of your drives (or folders, etc).
It still works on every version of Windows I run, from 95 to Win10Pro&Ult.
http://www.win.tue.nl/sequoiaview/What it does is analyze the folder and file allocations on a 'disk' (any type, or it can display folders), map them out, then present their 'appearance' to you in a visual display.
That disk allocation view can be displayed and/or filtered in various ways. The display will look like a (colored by type) checkerboard of various sized squares and rectangles.
Overall, the visual effect lets you see just which folders/files are using your disk space, sorted by size, or whatever parameter you choose.
Seeing massive 20G chunks of disk space is made easy.
Then, once identified, it's up to you to decide what to do.
SequoiaView, IMO, is one of the most useful programs ever, it's bulletproof too, it's just does what it says. Version 1.3, written in 2002, still working on Win10.
When you need it, I don't think anything else comes close. You can use many other 'file explorers', and set filters, etc., but not as simply or as graphically as SequoiaView.
It works great once installed, go through it's options applet and tweak it to suit.
Welcome to the SequoiaView Homepage
SequoiaView 1.3 was launched November 2002
Standard treemaps often lead to thin rectangles. We have developed a new method to display files : Squarified treemaps. The screen is subdivided such that rectangles approach squares as closely as possible. The screenshot gives an example.
Ever wondered why your hard disk is full? Or what directory is taking up most of the space? When using conventional disk browsing tools, such as Windows Explorer, these questions may be hard to answer. With SequoiaView however, they can be answered almost immediately. SequoiaView uses a visualization technique called cushion treemaps to provide you with a single picture of the entire contents of your hard drive. You can use it to locate those large files that you haven't accessed in one year, or to quickly locate the largest picture files on your drive. The screenshots below give a first impression of the original cushion treemaps:
SequoiaView was developed by the computer science department of the Technische Universiteit Eindhoven and can be downloaded for free from these pages. For more background information click one of the links on the left. Click here to download SequoiaView (approximately 500 Kb).
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http://www.softpedia.com/get/System/Hard-Disk-Utils/SequoiaView.shtmlJul 06, 2016 · SequoiaView is an application developed to offer you a different way of viewing how different folders occupy space on your hard drive and just how much of it.