To verify wether it's a rendering or modeling problem, try it in r the Poser 4 renderer. If the problem still remains, it's probably a modeling/posing problem. If not, it is probably fixable with a few tunings in the render settings. You might want to try enabling polygon smoothing and playing with the material's transparency falloff and transparency edge settings. In order to get rid of the slight overlapping in at the left hip/upper thigh, you can add a very slight displacement to the clothing prop's displacement channel. This will lift the prop's polygons away from the figure just a tiny bit.