I had a Facebook game, made with Unity utilizing NGUI. When the game loaded up for the first time, Facebook's dialog showed asking for permissions. To do this, the Unity container of the game is minimized.
The problem is when the game regained focus, some labels of the game were HUGE (And I mean huge, I could tell it was a label due to the color showing up, which was all I could see).
This happened everytime the game resized.
The problem was, in fact, in the labels. I had to make sure that all the labels had the Keep Crisp option set to "Never", so it wouldn't try to resize it and make everything weird and broken.