You can search for this bug and it seems like it may be related to ecryptfs and is many years old. The symptoms are that you return to the computer and the screensaver was active or the screen was asleep/black and it doesn't seem to come back. But you check by SSH the computer is running fine and are frustrated you'll lose your running programs and have to reboot. There is a simple solution: Ctrl + Alt + F1 Ctrl +Alt + F8 Ba........

[1035724.274610] [drm:intel_pipe_update_end [i915_bpo]] *ERROR* Atomic update failure on pipe A (start=62076478 end=62076479) time 102 us, min 894, max 899, scanline start 893, end 900 W: Possible missing firmware /lib/firmware/i915/kbl_dmc_ver1.bin for module i915_bpo I've been getting those errors on a J3455 NUC box with the latest kernel on Linux Mint 18.2. When updating the initramfs I also got the error about the firmware........