I think the idea of solving a whiteboard problem can be fun, providing it's unique. Quite a few times while looking for an internship I was asked mostly standard problems out of "Cracking the Coding Interview" or similar. Under pressure, even problems I've practiced or just understood from a contextual standpoint can be tough. Personally I have issues with the usual situation of it - interviewer staring, which is intimidating, and/or not even trying to have a mutual conversation and bounce ideas around to ease some of the pressure.