Extreme increase in Disk Space taken

Just a few weeks ago, I started noticing my computer was slower and slower and responding on programs, which I found rather weird, as I've only downloaded some movies the last entire month (Porn not included.) - But there, a virus might have slipped in.. I am not sure though, as Malwarebytes, Adwcleaner and CCleaner haven't really affected anything. (Yeah, I know CCleaner just cleans up, but it hasn't decreased the sudden increase in HD space taken)

As you can see.. The black line shows how much space was left, just a few weeks ago.

I'm running Windows 7 64-bit

/Immediate update, I just removed a lot of files, it just took up additional 3 gb.

via Bleeping Computer Last 20 Posts http://www.bleepingcomputer.com/forums/t/512687/extreme-increase-in-disk-space-taken/