Adding gigs?

For some reason, now when I defragment on my normal c drive.. it adds gigs to it, and I dont know why.

When I first got Defraggler it worked fine, it did what it was supposed to and decreased the amount of space I had on my c drive, now when I analyze, it tells me it wants to do 17 gigs or something, but instead of decreasing the size of my drive by 17 gigs it adds 17 gigs. This is the second time, first time it added 15 gigs.

Why is it adding gigs to my computer?

Are you using Windows Vista?

I ask because if so this has been discussed a LOT on the forums here and it is the result of Windows creating Restore Points when the files are being defragged... They get overwritten by new Restore Points as they are made though, so that shouldn't be a big issue. I would still like this to be resolved, but thus far it has not.

Hope that helps.