I just solved it...It was a external USB drive that appantly screwed it up. Unpowered the drive, plugged in the SATA disk..booted up and it worked and then connected the external drive again.
Will I have to do this every time?
Check the boot order in BIOS and remove all USB drives from there. Other than that, you can always safely remove the drive and use yours, this shouldn't cause issues (the plugging in and out of an external drive).