Cannot Empty Recycle Bin--shows only one deleted item at a time

I have a 105GB hard drive on a Lenovo (Thinkpad) 3000 N100 running Vista with 2GB RAM. It runs well enough, but Explorer ("Computer" from the Start menu) shows that the drive is completely full. Vista obviously believes this because I get "disk full" error messages when I try to copy large items like PST files. The disk cannot really be full. I don't collect music or video, I don't download much, I run only standard stuff and really not much of it (Office, mostly), I pretty much know what I'm doing, and the computer is not yet a year old. So, I ran WinDirSat and it shows only about a third of the drive is used. I attach screen shots. I think the problem may be with the recycle bin. When I "open" it, it shows only one file at a time. When I "empty" it, that one file goes away, but when i refresh the view, a new file shows up. I "empty" that one, and another shows up. I can do this all night and I never seem to reach the end. Any ideas how to fix it? Any other ideas on what the problem might be? Many thanks.