So, i am installing windows on my mac via bootcamp. i have already done it before using parallels, and it worked perfectly.
Using the same disk (i have another license code). i tried to install windows using boot camp, when i press enter to start the installation, i just get a blank black screen. Nothing happens it just stays there. and after 1 minute, the disk stops spinning.
Try the same license code as the one you used for your friend.
Another Option could be memory. Make sure your gave your Windows Partition enough memory. So you might want to boot into Mac Os, then remove your Partition then start another one but give it a fairly decent size. 20-30GB is probably good. (Depending on what Version of Windows.)
Good Luck, and post back here if it still doesn't work.