The red light means you have jammed the digital audio jack by inserting an analog plug too far. It is not a BootCamp issie--can happen to people without BootCamp. Here is the reason for the problem I posted in another thread:
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Background, or "why this happens": the audio-out port on a modern Mac is digital and is held to high dimensional standards. Most headphones have an analog plug not made to such standards. The specific issue is the the "tip-to-stop shoulder" distance on many analog plugs is just a bit longer than on a digital one and jams the "mute" contact inside the port in the muted position. <deleted>'s advice to insert a plug and gently wiggle it in the horizontal plane is exactly on target unless you are under warranty, which would still necessitate a trip to an Apple store for service.
The best action is prevention. When connecting headphones (or external speakers), put on the headphones and have an audio track running BEFORE you insert the plug. Insert the plug slowly, listening for sound on both channels and, when you hear it, STOP INSERTING.
Bottom line is you do NOT want to insert any random plug "to the hilt" until you know it is dimensioned to fit a digital port.
My MacBook Pro has the same jack. I have a pair of decent-quality, name-brand headphones and their plug is not to spec. This picture shows their plug in the port at a position that delivers proper sound and does not let the plug fall out:
Note that the shoulder is about 1/16-inch from contacting the computer case. It is secure in this position.
Every plug is different. I have a pair of El Cheapo external speakers I picked up for US$2 at a yard sale and their plug fits perfectly on my Macs with a digital audio port. Go figure!
