Hi! I use my MacBook at home most of the time since a few weeks so I don't know since when my MacBook got this problem (when I use it at home I usually have my home cinema system connected to the MacBook, however, it's connected with a normal 3,5" stereo jack (like normal headphones have). Once I unplugged the cable by accident and realized it when I wanted to turn the volume up when I didn't hear anything and the icon (which appears when changing the volume) was a crossed speaker icon. When I checked the cable I saw the red light coming out of the headphone jack. I plugged the cable back in and it worked like it should, but when I unplugged it the audio output switched to optical again instead of the included speakers of the MacBook. I tried turning the MacBook on while everything's disconnected - you can hear the self diagnostic sound or how it's called - and when I'm at the login screen and hold my finger next to the headphone jack I see the red light again. I tried booting up Windows Vista (which I have installed on it) - same result, so it seems not to be a software/driver problem :-( Anybody got an idea? I'm using Leopard 10.5.4 on a MacBook 2,1 with 2GB RAM.