Not a problem. Thanks for the virtual beers. :)

For future reference, Euler rotation keyframes in the Graph Editor are displayed as squares; quaternions are displayed as diamonds.

Yeah, I saw...

kal,

Got your file, and I think I've figured out the problem. The rotation interpolation of your shoulder control curves is currently set to Synchronized Quaternion. A quaternion rotation...

Kal, wanna post the scene file for me? It's hard to troubleshoot rigs without actually playing with them.

And yes, I know what you're referring to about Jason's rig. I use a similar approach.

How is your character rigged in the shoulder area? Do you have a control for the shoulder or are you actually animating the joints?