Hello.

Though I've never created any meshes for Poser I have worked with dynamic cloth extensively in Poser.

One thing I've noticed when particular parts of a mesh start "exploding" or doing weird things, the problem is often in the vertices selection process. Even though you drag-click a box over  an area, sometimes not all points in that box get selected and you have to zoom way in (obviously you should be viewing things in wireframe mode) and  make sure all the points you want selected actually are.

Dunno if this will help but it was the first thing that came to mind =P