I'm not sure where to put it. The error is typical for Windows, but I haven't booted it for a month or so. I have MacBook Pro 13" mid-2012 (last non-retina). The only difference to a tock configuration is SSD drive Crucial MX300 525GB that I installed over half-year ago. I also have 2 operating systems installed (each one on it's own partition): macOS Sierra and Windows 10 Pro using Bootcamp. Today, like every morning, I put my MacBook to sleep (running macOS), put it to my backback and took it out after I arrived at work. I didn't notice a macOS user password entry screen, instead there was a black screen with: "A disk read error occured Press Ctrl+Alt+Del to restart" I suspect, the laptop rebooted by itself, because I'm sure I didn't switched it off and I didn't touch the power button. Ctrl+Alt+Del of course doesn't work, so I had to do hard reset. If I don't touch anything after reboot, any OS doesn't load, I'm getting the same error. And now, most interesting: when I hold the option key to access boot menu, every time I'm getting different combinations of systems to boot into. In approximately 50% of the cases it is as expected: "Macintosh HD" and "Windows", but randomly I'm getting also: - "Macintosh HD" only - "Windows" only - "EFI Boot" and "Windows" - nothing (only WiFi selection dropdown) - "Macintosh HD" and "Macintosh HD" (the same, but twice) Whatever I choose, I am always getting an error mentioned in the thread title. If it matters, I noticed that couple of times, when I didn't select anything for a while (about a minute), all the disks disappeared and only WiFi selection remained. EDIT: I just noticed that my post contains only description of the problem and no question asked. Did anyone encounter a similar issue on a recent OS? I found something similar already, but all problems were related to old Mac OS X (like Lion) and Windows 7 (or even XP). Nothing new for Sierra/Win10 combination.