Phonon audio effects let hang the app when changing the source media

Applying audio effects like the equalizer to the current playing media (a MP3 for example) works. But as soon as playback is changed to another media file by calling "setCurrentSource" on the used Phonon::MediaObject, the application hangs forever and even stopping it through the task manager isn't possible.

One can reproduce this issue using the demo "qmediaplayer" found in the "QtSDK/Demos" folder:

1. Build the demo qmediaplayer and install it on the phone
2. Open and play a MP3 file
3. Choose an audio effect like the equalizer, configure and apply it
4. You should hear a difference immediately, because the equalizer works now; so far so good
5. Open and play another MP3 -> The app hangs forever, even closing it with the task manager isn't possible