Your hard drive maintains a catalog of files and the segments to which they are assigned. Files are not necessarily stored in consecutive segments (fragmented hard drive). If the catalog becomes confused, which it can after several crashes, errors will be reported.

Disk First Aid is a first level repair program. It will repair minor directory and catalog damage. However, if it finds damage that it is not equipped to fix, it will return a message similar to the one you got. Then you need to go to the more robust repair programs. I use Disk Warrior (Alsoft), TechTool Pro (MicroMat) and Norton Utilities (Syamantec), in that order, to repair damaged drives. In the large majority of cases, these three will be able to repair any damage.