Orange Furball
macrumors 65816
Randomly I found this red LED shining out of my MacBook... its coming straight from the headphone jack. I thought it was a laser but its just an LED I guess... what's causing this?

The optical audio out has been enabled.
Remove the 3.5 mm plug you use to connect the speakers to the Mac from the Mac's audio out port, and see, if there is a red light. If so, repeatedly plug and unplug the 3.5 mm connector until the light goes away, as the red light is the indicator of the digital, optical audio out being enabled, and sometimes it just gets stuck.