If you have Poser 4 PP or more recent, you can go back into the setup room and manipulate the hand directly until it is right, or in the pose room, select the bone that is a problem and then activate the joint editor and play with the xyz dials until those stray vertices bend the way they should. Of course, work on one side at a time and use the symmetry option under figures so you don't have to do it twice. :O)