I've searched the forums for the same problem, but to no avail. I hope you guys can help me. My headphone jack on my Macbook Aluminum 2.0 with 10.5.7 suddenly is blocked! I can't fully insert my headphones into the jack. I already tried slowly wiggling the plug to "un-block" but no help. I tried to slightly forcibly push the the headphones into the jack and still unsuccessful. Is there an auto-block feature in Macbook headphone jacks that I don't know? Please help.