It ether means your drive is failing or the corruption is such that disk utilities can't repair it. If you have important file on the drive you need to save. You would need to buy a stronger disk repair dvd. Such as DIsk Warrior. Otherwise,erase the disk and reinstall the operating system. Which depending on the damage, might work.If you have been backing up your file all along then the option to reformat and reinstall is the way to go.If you are running a newer operating system with a recovery partition you can use this to reinstall. Except if you were running maverick as since it is no longer available. Even trying to use it on internet recovery doesn't work for some reason.If you have yosemite and can re-download it from the app store, you could make a bootable installer to do this.