Please also post the output of: # dmesg | grep usb I am in particular interested if the kernel recognizes your USB scanner device like "new full speed USB device" or as "new high speed USB device" The latter case can cause issues when your USB scanner is acually only a full speed USB device (i.e. USB 1.1) but the kernel operates it as if it was a high speed USB device (i.e. USB 2.0).