Help with audio in MBP

[Sdahe]

Hello,

I few minutes ago I click on the volume buttons and I got a strange icon in the display. This is what I got...



If I plug the computer speakers to the line-in it works fine. Another wierd thing is that I can see a red light inside the line-in jack... wierd!!!... need help

 

[t0mat0]

Red light is the optical out.
Speakers for a current MBP normally into the nearest left hand side 3.5mm jack