Hi, thanks for your interest in my problem.
I run the programme you gave me. It described the usage of my hard drive very precisely. The bad thing is that it ascribed only 55.2 GB as a size of the disk, whereas when I right-click properties on the C: it tells me 143 GB (which I believe is the real capacity of the hard drive) . The programme just didn't detect the rest of the disk, which I believe is hidden in undeleted backups from system restore point. I turned off this function of the vista but the backups didn't eraesed, but went in the hidden system part of the Windows, I believe... :huh: