Here's what is happening. The sharp crease where the strings hook to the bikini bottom are being automatically divided into separate groups. The next polygon over is less than the 80 default and is not being divided, it's smoothed. This change from smoothed to unsmoothed produces an artifact. (One end of the facet is folded, the other isn't) When you see this happen don't look at the burned facet for the problem, look to the next facet over.

If you want, you can change the default crease angle in properties. You can also create smoothing groups inside Poser with the grouping tool. Using the smoothing groups is probably the best solution if your item is to be a Poser 6 only item. If it's to be a P4/5/6 item set the crease angle up so it matches the P4 behavior. Nerd3D