Maxxx; Do a thorough inspection around the model, particularly the hands and feet. You get this effect if there's is a collision violation, and the very small polygons in the hands and feet make it rather easy for them to penetrate between the much larger vertices in the cloth...then when you get a vertex/vertex collision....boom. It doesn't have to be extremities, though. Anything that is set for collision detection can do this (nipples, jewelry, a prop on the body that's activated as a collider with the figure, etc). If there is a high poly constrained group that interacts with a low poly cloth group (like say a shirt flap being penetrated by a 'rigid' belt), it does the same thing. For that matter, if the cloth interpenetrates itself, it stops dead. If it's the extremities, then Nerd has some freebie low poly mitten and bootie props that attach to the hands and feet to act as collision surfaces (invisible, of course, so they don't interfere). But this can be a pita to find; all it takes is one vertex....