I had to leave my computer running overnight on 15 April (16th April Australian time) and when I tried to restart it the next morning, nada. Couldn't even boot in safe mode from bios. I didn't have any clues as to what had happened or what caused it but it now seems that it was caused by Malwarebytes. As I had heaps of stuff on the drive I couldn't afford to lose I was forced to take my hard drive to a data recoverey firm and that little exercise cost me a cool $680. My fault for not doing a backup, I know, but that doesn't excuse Malwarebytes either.