I really don't know if this is a glitch or what, but I occasionally have a problem with child objects, specifically when rotating their parents.
Basically, my problem begins when I make an object another's child, and later rotate the parent. Instead of just rotating along with it's parent, the child stretches and deforms. If it's a cube for example, it'll become more of a parallelogram when it's not at it's default rotation; and the further it is from it's default, the more warped it becomes.
Has anyone else encountered this problem? Bear in mind it doesn't always do this, only rather seldomly.
Agreed, as per Matt(Trip)Maker, it must be something relating to scale. This is probably the best 'answer' on this page!
– AlucardJay