Buzz Out Loud Lounge: Vista showing false Disk space

Vista showing false Disk space

Something strange happened on both my laptop and desktop computer recently. When I checked the estimated disk space I my computer had left, I was surprised by what I saw. The hard drive on my computer has the capacity of 250 Gb for Windows (my personal files-ie music, pictures documents-goes into second hard drive. Usually, I have around 10 to 20 GB used up on the Windows HD. When I saw that there was 130 GB used on my computer, I couldn't figured out what I had installed recently that would take 100 GB or so. I kept checking and checking to make sure, but the math didn't add up. So finally, out of a hunch, I decided to defrag the hard drive. Incidentally, the disk space started to free up. Strange, yes? I have no idea what's going on. This happen on both my laptop and desktop. I was wondering if anyone have this problem as well.