i have an intel macbook running leopard with the most recent update. A problem arose a day before the update was installed wherein my macbook no longer transmits sound through the headphone jack. i have no reason to suspect a hardware failure, there has been no damage to the computer. is there any way this could (please, god) be a software failure? and if so, one that i can fix? please help! you guys have solved so many of my dilemmas, i hope you can keep up the good work! thanks for the help!