content: I have an ASRock Z77 Mobo (Sub company of Asus) and this just happened to me last night. It fucked up the MBR so I couldn't even boot with the  secure boot off. Basically I've had to reinstall windows on the drive and wipe everything. I didn't lose anything because I don't keep important things on the OS drive. But I was so fucking mad because MS has made installation such an insane pain in the ass its unbelievable, I was ready to start fist fulls of broken glass up MS executive assholes.