SP3, W10, SP4 type cover No malware (checked with several tools) No home-built or strange software Business only - no games or entertainment This unit is more than a year old, and has performed brilliantly. I periodically clean up my Windows computers with a system restore (my data is mostly in the cloud), and did so about a month ago. Here is the current (3-4 days) problem: At startup the screen will sometimes remain dark. Light bleeds in at one side, so something's working back there. No combination of keys (that I've discovered) will continue the boot to the startup screen. Ctl-Alt-Del does nothing, no swipe works. But the machine is not dead - there's illumination behind the screen. Holding down the power key will EITHER 1. produce a half-screen image, asking me to swipe down to complete shutdown. That works, but goes back to the initial problem. 2. directly shut down I've introduced new stimuli, including closing the unit, detaching the keyboard, random key combinations, etc. but with no consistent results. The correct pen driver is installed sfc /scannow reports corruption, but "...some problems could not be corrected" MRT finds nothing Various external scanners find nothing ??