Hi, this morning I experienced a bad issue that worried me for a while, but happily it ended well with no consequences.
After resuming from suspend, the monitor was black, and I had to press the power button to hard shutdown the computer. On reboot, the monitor still didn't switch on. I tried several times. In the last tries the monitor switched on, but the keybord still didn't work. This affected the boot loader as well. The system booted up, and I got the login screen, however no key worked (apart from the power button, it's a MacBookPro 12,1). I brutally switched off the laptop, and leaved off for some time (1 hour). When I tried and rebooted it, everything worked well again. I inspected the kernel messages, and found the following usb errors (keyboard and monitor are USB devices on the MacBookPro 12,1): ==== Mar 29 09:06:25 alan kernel: usb 2-3: device not accepting address 2, error -62 Mar 29 09:06:36 alan kernel: usb 2-3: device not accepting address 3, error -62 Mar 29 09:06:55 alan kernel: xhci_hcd 0000:00:14.0: Stopped the command ring failed, maybe the host is dead Mar 29 09:06:55 alan kernel: xhci_hcd 0000:00:14.0: Abort command ring failed Mar 29 09:06:55 alan kernel: xhci_hcd 0000:00:14.0: HC died; cleaning up Mar 29 09:06:55 alan kernel: xhci_hcd 0000:00:14.0: HC died; cleaning up Mar 29 09:06:55 alan kernel: xhci_hcd 0000:00:14.0: HC died; cleaning up Mar 29 09:06:56 alan kernel: usb 2-3: device not accepting address 4, error -108 Mar 29 09:06:56 alan kernel: usb usb2-port3: couldn't allocate usb_device ==== It seems that some rest is sometimes needed ;-)