Ever since my computer had to restart after installing this very nasty backup software that comes with Toshiba portable external drives, I have had CHK DSC run every other startup. It never gives me any error messages that I can understand. Yet, once when I did have a problem and ran file checker, it found the error and completely fixed my problem. What is the difference between the two? With the way Win 7 files seem to "drift" and sometimes get inadvertently dragged around, wouldn't running file checker be a good first place to start with many problems?