Update October 10th: I found out my game wasn't optimized well for low end PCs and when the frame rate gets below 5, Vadine can be thrown across the map until he hits an unmovable object. This made the game appear buggy...
I put in a patch today and I'm seeing a consistent 60 FPS on all of my computers, including my mac mini and a 2.0 GHZ Dell computer without a graphics card!