Yes, I have lots of songs, currently a little bit more than 2,000 and it is constantly growing up. But since the version 'build-893' (I had about 1,400 songs) it just happend two times. If I delete the app data and restart the app it works fine again. I don't want to delete the app data again.
EDIT: I tried now this: I deleted some apps for more internal space. Then I moved Poweramp from the internal storage to my sd card (this works on my Xperia X but not on my other devices). Now the app works without problems. If it brokes again I will post it here.