I have Yosemite 10.10.3 on a 2010 Mac mini Server. Although it doesn't have an optical drive, this specific model doesn't natively support installing Windows from an imaged USB thumb drive, for some reason. Thankfully there are lots of tutorials online on how to remove a single string in the plist file in the Boot Camp Assistant application package contents and re-signing the application. After doing this, BCA gives me the option to create a bootable USB installer from an ISO, which I did. I had BCA download the latest drivers, partition my Mac's second internal HDD for Boot Camp, and download support software as well as install Windows 7 following an automatic restart. Well, the Mac restarted but a Windows DOS screen immediately loads and says "Non-system disk. Press any key to reboot." If I boot up holding down the Option key, the bootable USB Windows installer created by BCA doesn't actually show up. I don't have an external optical drive and I've tried everything I can think of. Two different brands of flash drives, the USB port closest to the power cable, using Boot Camp Assistant to create the bootable installer, et cetera. It may be that since my Mac doesn't natively support installing Windows from USB that BCA didn't do the final step in making the USB drive bootable. Is there a way to manually do this from a Mac or PC on the thumb drive thy already contains the Windows installer as imaged from the ISO? I'd love to get a Windows 7 up and running on my Mac. Thanks for any help!