Mac OS X 10.6.8 not storing password in system profile - used for pre-authentication to the wireless network
Make sure that you haven't enabled the security settings in System Preferences -> Network -> Wi-Fi (Airport?) -> Advanced -> Wi-Fi: "Require administrator password to:"...

It may also help to examine log files on the computers that are having the issues. Best place to start is probably the log at /var/log/system.log. If you're using RADIUS, it may help to enable EAPOL logging:

sudo defaults write /Library/Preferences/SystemConfiguration/com.apple.eapolclient LogFlags -int 1


To disable EAPOL logging, you can perform this command:

sudo defaults write /Library/Preferences/SystemConfiguration/com.apple.eapolclient LogFlags -int 0


You may need to reboot after applying this command. The resulting log file should be located at /var/log/eapolclient.&lt; interface >.log (e.g., eapolclient.en1.log)