Thank you Joseph for your support. Concerninig the context of this issue: I had an old Ubuntu 12.04;  I decided to upgrade it to 18.04 version and, in the same time, to upgrade the hardware of my old PC: Asus M/B AMD A320M-C (AM4)  as motherboard, and AMD CPU Ryzen 3 2200G (AM4) as processor. This hardware upgrade was a mistake : -the kernel didn t manage very well the new Ryzen CPU+GPU processor: as system was very unstable, frozen at any time I finally had to install a graphic card to bypass the gpu included inside the Ryzen chip; automatically all problems dissapeared... -however I found out another issue: trying to restore my data stored in an external USB disk I realized that the kernel didn t detect 2.0  USB devices , and 3.0 USB devices were detected but followed just after by a system crash... I guess this is a issue with the new motherboard and/or its BIOS/UEFI (I could retrieve my data with ftp from another PC of my local network) I will try to follow your advice and test with the 4.17 kernel. Thank you again Enviado desde Yahoo Mail para Android El mar., 1 de may. de 2018 a la(s) 15:01, Joseph Salisbury