Problem is due to maemo's extra repository that provides a special version of libsdl-mixer1.2 (lversion 1.2.6-5+0m+ogg+mp3 instead of 1.2.6-5+0m)

first disable maemo extras , maemo-devel and testing then type in xterminal
root
apt-get install libsdl-mixer1.2=1:1.2.6-5+0m5


same goes for libsndfile
apt-get install libsndfile1

hope that helps