hard drive appears nearly full but is only 25% used

I have vista home premium, 200gb hard drive. i had not been paying
attention until I received a warning that I was running out of space.
Being sort of a dummy, I took computer to Best Buy. They ran
diagnostics. They found no problems. Then they cleaned it up and
optimized it. When I got it home the C drive showed 177gb capacity with
135gb free space. Within 3 days my free space was reduced by approx
25gb. I downloaded and ran Auslogics Defrag and my free space was again
135gb. But in the last 5 days my free space has been disappearing. It's
at 113gb right now. I realize that's plenty of free space, but I'd like
to rectify this problem before I'm close to showing full again. Can
someone help me?

Posted via http://www.vistaheads.com