Phonon::MediaObject setCurrentSource() second time crashing app

[been_1990]

private: 
Phonon::MediaObject *mediaObject;
 
//ADisplay.cpp
     void ADisplay::setAlarm(QString alarmSound){
     QUrl alarmS = alarmSound;
     mediaObject->setCurrentSource(Phonon::MediaSource(alarmS));
}

private: 
Phonon::MediaObject *mediaObject;

//ADisplay.cpp
     void ADisplay::setAlarm(QString alarmSound){
     QUrl alarmS = alarmSound;
     mediaObject->setCurrentSource(Phonon::MediaSource(alarmS));
}

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Here whe have the bug:
mediaObject->setCurrentSource(Phonon::MediaSource(alarmS));

But only when it's created the second time:

display = new ADisplay();
                display->setWindowFlags(Qt::WindowStaysOnTopHint);
                connect(this,SIGNAL(soundAlarm(Al*)),display,SLOT(showDisplay(Al*)));
                connect(display,SIGNAL(quiting(QString)),this,SLOT(quiting(QString)));
                emit soundAlarm(a);

display = new ADisplay();
                display->setWindowFlags(Qt::WindowStaysOnTopHint);
                connect(this,SIGNAL(soundAlarm(Al*)),display,SLOT(showDisplay(Al*)));
                connect(display,SIGNAL(quiting(QString)),this,SLOT(quiting(QString)));
                emit soundAlarm(a);

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First time the above works, second time, bug.
Attachment 4598