I ran into a problem creating Poser Shaders for my S.E.Asian Shields - not a show-stopper, just an irritation. I've only noticed it happening in Poser 6 (v6.0.3.140). Haven't seen this problem in Poser 8 or Poser 9 yet, but most of my testing has been in Poser 6.

Okay, so what exactly is the problem?
The attached image shows a very simple shader using 5 image maps, two of which are set to 'None' by default, the other three use various images.

...If I select one of the Image_Map bricks which have an image (i.e. 4, 7 or 11) and set Image_Source to None, then although the text for Image_Source is correct (i.e. 'None') the preview image (and the image used when you actually render) appears to be a random one (as far as I can tell it's always a random one from the images currently/already used in the current shader on the current material during the current session, but I wouldn't swear to that. (I'd guess the root cause is possibly that a pointer's getting screwed up in the code somewhere?)

Q1: Has anybody else seen this problem?

Q2: Is this a known bug in Poser 6 that's already been fixed for a later version?

Q3: Is there a way to fix/work around the problem (I currently delete the brick and add a new one).

I have a blank (white) image I use as a placeholder. I havent seen the problem in P5 or P7 but I cant say its something I have done very often.

This happens sometimes in P7 as well.  I noticed it recently when I was doing a scene with lots of little houses and one human figure.  The color image for the house siding was in the wrong folder.  Instead of leaving the siding blank, Poser decided to apply the floral image from the human figure's blouse.  Took me a while to determine why the houses had murals instead of shingles on their walls! 

markschum - a blank image seems a better generic workaround than the 'disconnect the image brick' or 'delete the image brick and add a new blank one' I currently suggest in the Readme.
ockham - slightly different problem but sounds like the same root cause, so it looks like it wasn't fixed in Poser 7. I'll play around in Poser 8/9 a bit more to see if I can get the same problem...