Insert the OS X install CD.
Restart the computer and as soon as you hear the startup chime, press and hold the "C" key to boot from the disc. You can release the "C" when you see the Apple logo and progress indicator.
Choose your language and click to continue.
When you are sitting at the Introductory Installer screen (DO NOT INSTALL), go up to "Utilities" in the menubar and choose Disk Utility.
In the left hand sidebar, choose your Mac's hard drive (usually "Macintosh HD").
*If you do not see the drive, stop here and let me know what, if any, drives are listed.*
On the right hand side of the page, click "Repair Disk"
If it finds errors, repeat the process until it reports the drive is OK.
Next, click "Repair Disk Permissions"
Once the process has completed, choose “Disk Utility” > “Quit Disk Utility” in the menu bar at the top of the display.
Then, restart your Mac.