Suggestions?

Running YDL 2.3 on an ibook. One of the first iBooks to come out *blueberry* flavour. Works & runs like a dream...all for one thing. Can't get sound out of it....so to speak... We tested the sound (in the mixer section of Gnome & KDE) & yes it indeed does play the test sound....quite lovely.....However pop a CD or play a MP3 & nothing. It plays the CD's & MP3's...just no music coming out of it's tiny little speaker. Bit baffled....any suggestions of what we can do to lead us on to the path of soundhood?