Hi, If found some time to dig in a bit. It looks like it has something to do with python-qt4, because the app.exec_() in /usr/share/hplip/ui4/systemtray.py:725 fails/locks it up. This is a call for QApplication to start, so it looks like something goes wrong here. Regards, Matthias PS: Not being able to kill PyQt-apps has this reason: http://www.mail-archive.com/pyqt@riverbankcomputing.com/msg13757.html