Now, I understand that the issue might be not related to xorg, but USB. Today, the system did not start X. At launching startx, EE was on ''missing'' /dev/input/mice. Unpluging: * the USB plugged printer HP DeskJet 6840 * the sagem fast 800 cegetel internet router * and the USB hub and repluging directly USB mouse (directly here means without hub). makes startx (and so X) work.