When I use the Disk Utility to "look" at my SSD, it tells me that I have used 90 GB of the 120 GB available. However, when I look at my programs and other files, and I run a MacKeeper scan of the drive, it appears that I have only used around 10 GB of space. I cannot imagine how 80 GB of space - more than half of my entire drive capacity, can be used up. Please excuse my ignorance - I just don't know where all that "data" is - or what it is. If I took all the photos and movies and music I have on an external drive and loaded it ALL into my computer, it would not add up to HALF of the 80 GB I am supposedly using. I can't "see" this dark matter anywhere - it's not in Finder. I can guess there may be some partition on the drive, but I didn't put it there, and I don't know how to look at it, or remove whatever data is there taking up so much space. Any ideas? Thanks for your assistance.