I too was having a similar issue after much trial and error I realized that I could select a boot device from my start up screen. I didn't want to risk harming my primary OS. I have three drives and can choose from my bios whether I want to boot from a CD/DVD or any of the three hard drives. When I power on my PC I have quick start disabled and i just hit F11 to choose my boot device.
I installed iAtkos Version 7 10.5.7 I don't know what your system is like but that is how I operate mine. Hope that helps you somehow, I'm no pro but I'm learning after each mistake I make.