Rick here are some basic maintenance procedures you can try if not already done:
Repair Permissions - /Applications/Utilities/Disk Utility.app. Start Disk Utility, select your HD and click on Repair Permissions. When finished, quit Disk Utility and then restart your computer.
Reset PRAM - hold down Option-Command-P-R keys when starting until you hear the startup chime a 2nd time.
Safe Mode Startup - hold down the Shift-key at startup until you see the login screen. When logged-in, then go to System Preferences/Network/AirPort
- click on the 'Network Name:' roll-button, select 'Join Other Network...', enter 'Network Name and select the security type you are using, and finally, enter your Password and click 'Join'.
- click on 'Advanced', TCP/IP and confirm that 'Configure IPv4:' is set to 'Using DHCP', click 'OK'.
- click the 'Apply' button and exit System Preferences.
You can delete the airport logins in your keychain and set them up again. Here is how:
1. Go to /Applications/Utilities/Keychain Access.app, select ‘login’ under Keychains, and select ‘All Items’ under Category.
2. Delete all airport logins showing under the ‘Kind’ column that say ‘AirPort network password’ or ‘AirPort base station password’ (make sure you write down your passwords first if you can’t remember them).
3. Select ‘System’ in Keychains, and select ‘All Items’ under Category.
4. Delete all airport logins showing under the ‘Kind’ column that say ‘AirPort network password’.
5. Click onto the Keychain Access menu and do Keychain First Aid.
6. Exit Keychain Access and reboot. Test airport connection – you will have to reselect your network and logon.
