Actually, scan disk does two things: it fixes broken chains left behind after an abnormal exit (i.e. BSOD) which happens with regularity when running Windoze. It also gives you the opportunity to delete chain fragments that get lost so they don't clutter up your hard drive. Secondly, it monitors the condition of your HD by alerting you to the presence of bad sectors. This is a good thing to know, as an increasing number of bad sectors lets you know your drive is about to buy the farm so you can back up your data and replace it before it fails completely. It's really a rather useful Windoze utility. Also, scan disk works much better and faster if you start it from the DOS prompt before Windoze actually loads.
