What causes a simulation to fail besides poke-throughs. That was the first thing I checked. I even tried not having any thing collide with it. It's been so long since I had a failure I can't remember what else to try. I'm using a figure converted to a prop although that has never given me trouble before. Any suggestions?

 If you have "cloth self collision" on, that might also be more than Poser's little brain can comprehend ;)

Also if the converted cloth is VERY polygon heavy - even in places - that can make Poser choke on it.

If object used in simulation has "non quads" polygons? - only suggestion.

I've found that converted conforming clothes often include things like buttons and belt loops that fly off into space during cloth simulations.  Generally, they tend to fly away from the figure and cloth item, but in your case, you may have one or two aberrant polies trying to intersect with others.  Unfortunately, they're usually very small and hard to find. 

My suggestion is to run a simple 15 frame simulation in which the cloth crumples to the floor.  Then look for any little "bits" hovering around the cloth item.

what are "non quads"? and how do I check for them?

quad - polygon with four 'sides' or edges and four vertices or corners.
non quad - other polygon:)

Switch to 'Flat Lined' display in Menu>(Document Style, Figure Style, Element Style)>Flat Shaded Lined (or whatever that can show the grid of your geometry).

Then you can see at first glance what the cloth is made of.
 

They are quad-polygons. So that variable should be correct, right?

I give up:)

Try setting everything up from beginning (close Poser, open clear document, load your fig .... you know the story) - or maybe you've already done that:)

I've done that. I re-started poser and tried a fresh simulation without out anything. Still didn't work. there are numerous "identical points in the face" and some "identical vertex index in face". could that be it?

"identical points in the face" and some "identical vertex index in face" - don't quite understand (so that must be it:)

But  you can still try with another cloth geometry (just to check) - if all goes fine than it means that that particular one is problematic.

edit:
"identical points in the face" - it means you have duplicated vertex in that obj. You coud try to clean this up with some modeling program - or change that figure one more time to an object.