What about unplug usb device, run "sudo tail -f /var/log/syslog" in a terminal un plug usb device again? It shows nothing special: Jul 3 01:21:38 eltron kernel: [ 91.573524] usb 2-2: USB disconnect, device number 3 Jul 3 01:21:43 eltron kernel: [ 95.904089] usb 2-2: new high speed USB dev...