Animations taking the wrong path to get from pose to pose

My timeline:
http://i.gyazo.com/30d970174ef0fb4d00b628fb4e455b02.mp4

How it plays:
http://i.gyazo.com/46e966f009a1a8246d582e47449391f9.mp4

The arms are supposed to go around in circles, but for some reason instead of going from the last animation to the first animation they loop all the way back around.

File: Dropbox - Error - Simplify your life

It seems that the problem occurs when you have the arms pointing straight up. It’s like they don’t know which way to go from there.

I very very slightly rotated the straight-up parts towards the direction that they’re intended to spin and tada.