I have Windows 8.1 and Ubuntu installed. I had ran boot-repair since the os selection menu wasn't showing.
A few days ago, I downloaded the latest version of Kali Linux. I used PowerISO to copy all the files to a 16GB usb stick(USB 3.0). I rebooted. In the menu when booting, I moved 'USB HDD' to the top of the list and saved.
This is exactly what I did when installing Ubuntu. With my USB stick inserted into the usb port, I hit the power button of my laptop... the purple grub menu showed up.
I rebooted few times, but it still showed the grub menu. I booted into Ubuntu and ran a md5 checksum. Everything is ok.