I found the same problem with DAZStudio, but here it is for PoserPro2010:

I've been saving some ballet animations. When a character turns and moves, the character slips below the ground level. I've tried scrubbing through the animation slowly and adding keyframes every time I see the dip below ground level occurring. But, this results in a animation where the character bobs up and down in a jerky fashion. Is there a way to keep the character at floor level? 

In a similiar vein, if I rotate a character, she/he may slip off balance. Trying to correct with keyframes results in a jerky, gyroscope-like, motion. Is there a way to set the character so that she stays centered over her hip or axis line?

 

If these fixes aren't possible, is there an animation program in which I might use characters like V4 and M4 and create animations for them?