Hello Rita,

Take a look at the "Try Disk Utility" section in this link: Resolve startup issues and perform disk mainenance with Disk Utility and fsck.

I think you need to select your language, and then go to the Installer menu and select Disk Utility. Do not click Continue in the first screen of the installer.

See also Mac OS X - Using Disk Utility to Repair a Disk. This link has some helpful screenshots for both Repair Disk and Repair Permissions.

I realize that this may repeat information you already know, but just in case it might be of use to others using the Search function at FineTunedMac.

Back up everything you can't afford to lose: documents, mail, movies, music, photos, and other data and settings.