I have a problem. As you will see from the following pictures, I made an skeleton and justa really basic shapes representing a human. I add IK handle to the arm (from shoulders to hands). Now, when I want to move ik handle the way you see on pictures, it's all good untill it gets to the second pic. Then, as you can see from 3rd picture, if I move this ik handle just a little, it changes it's rotation (I think around Z axis, you can see this from pic 3) for like 180 degrees just like that. This happens too me pretty often. How can I prevent this and make a nice arm movement?

I'm sure this is basic problem, but I'm n00b when it comes to character setup.

Tnx in advance!