using even W8 64 Prof with another HD had the same effect. Changing BIOS to Fast Boot enabled W8 came up with automatic repair preparation. The only difference was, changing the Fast Boot back, W8 booted again, W8.1 not.
But there should be no automatic repair preparation when changing to Fastboot.
FritzHajek, when you enable FAST boot, it automatically disabled some Boot ROM options. So when you restarted the system, the Master Boot record (MBR) detects an error on your system, therefore you are getting that message.
Since you already tried another operating system, I would recommend you to try a BIOS update to the next version.
If the issue persists, you can try replacing the motherboard.