Poser 6 had some problems with dynamic simulation, but a lot has been fixed in poser7 rn poser pro. Problems like this can be caused by lack memory as well Ram as on your harddisk, because cloth simulations need a lot of space for their files. But as you showed, this can also cause problems. Well for a first attempt  isn't it bad.

Bopper.

-How can you improve things when you don't make mistakes?