HD space dissapearing quick


Has anyone had this problem? For some reason, as I leave my computer on longer, my hard drive looses space. I have no clue why. But then the next time I restart, it's all back. My machine told me this morning, after leaving it on all night, that I lost 8 gigs. Now, the other day I did that whole swap partition setup thing. Did I maybe do that wrong?

Someone help please...thanks!