You just dont have the codecs to play your mp3`s
Because of Legal issues, Novell cannot include some software(or codecs for this case) with their SuSE distribution.
here you can see this.
it is very easy just use the YaST2 to install the rmps. A very good site to find them which i would recomend you is
this one.
be sure to get the newest xine-lib and the win32 codecs from the mplayer project.
(here). But I recommend you better try RPMs so YaST does not start complaining about dependencies which you do have. Good luck!