Not sure if this is the right forum for these kinds of questions but, I'm having trouble installing windows on my mid-2010 21.5in iMac. I've installed bootcamp (Windows 7 Pro 64bit), but could not boot from a disk due to a broken superdrive. I then created a windows VM and cloned the VM onto the partition (using this guide http://huguesval.com/blog/2012/02/installing-windows-7-on-a-mac-without-superdrive-with-virtualbox/). This caused a white blinking cursor and a black screen and does nothing, upon boot, just like this pic: . I tried an apple forum but they couldn't solve the problem (see here: https://discussions.apple.com/message/29278713?ac_cid=op123456#29278713I). Then I installed rEFInd and tried booting from the windows partition, bootable Windows 7 Pro 64bit usb, and a bootable Windows 10 Home Premium 64bit usb but still got the blinking cursor when booting. I tried a bootable ubuntu usb and booted it from rEFInd, and ran the "try ubuntu" just fine.