Note that the sim will force a distance between the cloth and a colliding object which is minimal the value as set in Collision Offset (which is in cm). When the sim cannot to that, results get a random, unmanageable character.

So when a single layer of cloth has to be manouvred between two objects it can collide to, like a dress between a body and a chair, then the minimum distance between body and has to be twice (so: take three times) the Offset.

When two layers of cloth have to be manouvred between the objects, or two parts of the same object, like the two pants of trousers covering both legs, the minimum distance between the two legs has to be at least three times (so: take four) that Offset otherwise the cloth will have issues colliding with itself.

When the distance between the objects surrounding the cloth is too small, you actually present the sim with the issue that it has to solve a math problem without being able to meet the conditions, so it goes wild.

So, in the "legs problem", when the original (cloth less) animation reveals that the legs are touching, you need to animate the thickness of the legs a bit as well to (re)create the extra gap to let the cloth pass in between.

Note: when cloth has to be manouvred in between colliding objects which are close, Poser needs a lot of tiny steps to do so carefully. So you need a serious amount of steps-per-frame in the sim settings. Doubling the steps will sort of double your calculation time, but will reduce your crashing risk as well.

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Usually I'm wrong. But to be effective and efficient, I don't need to be correct or accurate.

visit www.aRtBeeWeb.nl (works) or Missing Manuals (tutorials & reviews) - both need an update though