losing disk space when defragging

everytime i defrag using the vista defragger i keep loosing HDD space. the first time i defragged i gained a little but the past two times i have lost 6 gigs! ??? ??? ???

never mind. i figured it out. its weird though. i defragged once yesterday and when i lost 5 gigs i thought it was system restore so i cleaned sys restore out. didn’t do anything today. defragged again today and lost another gig but when i cleaned my system restore out today i gained my 6 gigs back.

:BNC ??? ??? ???