Follow along with the video below to see how to install our site as a web app on your home screen.
Note: This feature may not be available in some browsers.
It is likely the Windows page file; possibly the hibernation file as well. Those are both based off the amount of RAM you have installed, and if you are rocking 12, 16 or 24GB of RAM (not at all hard to do these days) then those temp files will eat up tons of disk space. Consider turning them off, or in the case of the page file at least setting it to something reasonable (or moving it to another drive).
Looks like I was typing while you posted some new info - sorry for the late links!
I personally would turn off the page file when you have that much RAM, but I know not everyone shares that sentiment. Joe Average on these forums has some good suggestions too - go to the "Operating System" forum category and do a search on "page file" to find additional threads about this.
I have 16GB and I leave it off completely. I'm also a heavy multitasker and I encounter no problems at all. Leaving it on actually causes slow downs because I feel when things are getting swapped. When I have it off I can minimize programs in the tray and come back to them at any time and they load instantly they way that they should. I prefer to leave everything in RAM and not leave it up for windows to decide.
Also Photoshop doesn't demand a pagefile anymore like it used to since you can specify a scratch disk that the program makes it's own temp files to if it needs to.
I do use hibernate though, gotta love that