When you import bvh animation files into Poser some tweaking is always necessary. I generally delete key frames so there is a key frame every 5 frames. However I find that with some bvh files, adjacent frames have body elements 360 degrees out. The element is in the same position but the the bvh regesters them 360 degrees apart. whilst the frames are adjacent this is not a problem but delete these two adjacent key frames and the animation tries to follow a course through 360 degrees . Is there any simple way to fix this ?

Aside from tweaking the frames manually using the animation graph, I don't know of any other way to fix it.