No Sound macbook pro Im playing music through my mbp 15" speakers and i keep getting a glitch were the sound will wont start playing i click on the sound up key and i get this icon, after a while (10 seconds) it goes away and i can get sound.

Any idea what might be causing it ? I tend to play music through headphones, but this error has occured when using the speakers..
It might think that you have connected an optical cable (is the port glowing red?) or that you are sending the sound through HDMI instead. If it's the former, try connecting your speaker/headphone cable and wiggle it a little. If it's the latter, check the sound settings in System preferences.