I've got a MBP 2.16ghz Intel 2 Core Duo. Been absolutely perfect since i bought in when it came out in October. Noticed today that when i put some headphone in the socket there is no sound coming through the headphone and sound is still coming from the speakers. ive tried different headphones but still the same problem. anyone had a similiar problem? there's no setting on OS X that could've have been tampered with to disable the headphone jack? advice/suggestions much appreciated.