1. Quit FCP.
   2. Open your Hard Drive.
   3. Set to Column View.
   4. Follow the path: Users > Name > Library > Preferences.
   5. In the Preferences Pane look for "com.apple.FinalCutPro.plist", shown below in Yellow. Drag the FCP plist to the Trash.
   6. In the same Preference Pane, look for the Final Cut Pro User Data Folder.
   7. From inside the Data Folder, drag 'Final Cut Pro 5 Prefs', 'Final Cut Pro Obj Cache' and 'Final Cut Pro Prof Cache', all three shown below in green, to the Trash.
   8. Do NOT empty the Trash.
   9. Launch FCP and check all your settings. All FCP setting will have reverted to default. Don't forget to reset your Scratch Disk settings.
   10. Once FCP is up and running, empty the Trash.