So I'm using the Disk Utility to erase free space on my Macbook (running Mavericks). I had 77GB available on my 750GB drive before I started this. It got about 80% through (using the 3-pass version) and then seemingly froze on "creating secondary temp file"--and my available space had plummeted to 8GB. Because it wasn't doing anything I chose "Skip," but now it's frozen on "Skipping" (at least an hour now), with an ugly warning as to why I can't quit Disk Utility. How do I get it to stop? Is this just something where I have to wait a day or so? How can I erase free space if it eats up all my free space in erasing it (which, of course, makes no sense)?