no sound anymore (even with mp3s) (1 Viewer)

[shotek]

hey, I installed the latest version of MediaPortal on my HTPC which has worked fine until today. At midday I wanted to watch a movie, but I realized that the sound doesn't work. The sounds of MediaPortal are still working when I switch between MyVideos and so on, but if I start a movie or even a mp3-file, I have no sound.
sound via coaxial (atm stereo)