Just unboxed a new MBP 13″ Retina and started the Bootcamp process to dual boot with Windows.  Once I finally got to installing Win 8.1, I rebooted to complete the setup and all I got was a black screen with a blinking cursor.  Searching around I saw lots of options for setting up a repair disk, etc. but being a fresh install I just wanted it to work “out-of-the-box.”  So I continued to investigate…

I suspected the issue had something to do with the hybrid GPT/MBR partition that Bootcamp creates so what I did was re-launch the Windows 8.1 setup (from USB) and deleted the (OS X created) BOOTCAMP partition and let the Windows installer create it.  Now works like a champ.