error loading operating system

I used Boot Camp Assistant to create a USB drive and a BOOTCAMP partition for Windows 8.

Starting up the system with OPTION/ALT and choosing the "Windows" partition results in a black screen, stating "Error loading operating system".

Trying to start in EFI mode results in an error while choosing the partition to install in. The error is something like ~cannot install windows on a MBR partition, GPT partition mode required~.