chkdsk /f is an option to fix the errors on your computer. For example, if you have shut down computer improperly/ system crashed - then chkdsk checks the disks for consistency or errors in terms of physica bad sector, bad file names, bad main file table.
If you are getting this error - your hard disk may developed bad sectors on it or some sort of file table coruption. it is necessary you run thE chskdsk. http://www.freesmileys.org/smileys/smiley-alien011.gif