Any time you have the arms down and the figures mesh is touching itself those polys from the dynamic clothing are getting pinched in between. Because the simulation doesn't always know what to do with those pinched polys you get what you see there, though that is a really mild case - I've seen much worse ;). You're options are to not quite have the arms straight down, or break out the smoothing brush on the morph tool and smooth down those areas. It does help quite a bit. Also, dynamic clothes need to be slightly higher poly than conformers because the fabric has to be prepared to go in any direction at any time and needs the extra density to do so. You will however sacrifice simulation time for that. It will make the simulation take longer. If you want to keep your robe low res you'll have to be prepared for results like what you have there that you'll have to smooth over. If you go denser you'll take the hit in extra time.

One more thing...you must make sure that no part of that dynamic robe is touching any part of your figure before the simulation. Sometimes that's hard to spot...hehe. A good rule of thumb is, if your simulation seems to bog down and stop or really slow down at times, it's intersecting with the figures somewhere. If it runs smoothly through you're in good shape.

Laurie