I am using Defraggler on a Vista machine. I noticed that the used space kept getting larger as it worked. I checked the drive properties afterward and the increase was still there. Then I ran ccleaner, but nothing got the space back. I think this has happened a couple of times without my noticing, because already a great deal of my drive space is unaccountably gone. I lost more than 10GB on that last defraggling alone.
HELP!