This morning, I was using my Late 2008 MacBook when I found that audio wasn't working. The volume icon in the menu bar was grayed out and System Preferences said that my output was set to Digital Audio instead of Internal Speakers like it normally is (and Digital Audio is my only option).
More surprisingly, the headphone jack has a glowing red light (I had no idea it could do that!).
Why is this happening? Can I do anything to fix it?