So my computer has about 4gb of free space on the hd. I leave for a few minutes, come back and see in the finder that there is 0KB! It also won't let me do anything, not even quit itunes because it says it can't save the library file. It's weird because the computer was idle, i'm pretty sure the only open app was iTunes. So I restart the computer but nothing has changed. So I transfer a bunch of files to an external HD then delete them. So I now have free space. I want to know where the space went though?? I opened OmniDiskSweeper to see what's taking up space and I see this folder called "private" that I've never seen before. Where is this located and could this be the space that disappeared? I included a screenshot so you can see where the folder is.