When choosing to repair or replace items in a system, you can choose from three levels of troubleshooting strategy. The procedures should be used in the order they are discussed here.
The following should be tried first when repairing or replacing:
Update drivers using Software Update preferences
Run -fsck in single-user mode to fix disk problems
Repair permissions using Disk Utility
Run AirPort Admin Utility
Run Directory Access and check settings
The following should be tried after the appropriate first choices have been tried:
Adjust user settings in System Preferences
Execute UNIX commands in Terminal
Reset PRAM by pressing Command-Option-P-R at startup until you hear the startup chime twice
The following should be tried after the appropriate first and second choices have been tried:
Perform Upgrade installation of Mac OS X
Perform Archive and Install installation of Mac OS X
Perform Erase and Install installation of Mac OS X
Repair the computer with Apple Hardware Test (included on disc with most current Macintosh computers)
Escalate as needed