you can prevent start of prl_naptd for managed-accounts with the following steps. Note: after this you will be able to access networking only in normal accounts:
1. Start the /Application/Utilities/Terminal.app.
2. Execute command "sudo mv /Library/LaunchAgents/com.parallels.vm.prl_pcproxy.plist ." without quotes. Note: this command will ask for your password and it will not be displayed while typing
ну или по-русски:
1 запустите терминал
2 выполните команду:
sudo mv /Library/LaunchAgents/com.parallels.vm.prl_pcproxy.plist .
точка последняя обязательна