Unless I’m missing something, you only posted one image – it would be more useful to have the screenshot and some of the images that aren’t matching. But there are a couple of possibilities:
Your solid color regions aren’t really a solid color and there’s dithering that isn’t consistent.
Since you’re testing Flash, it could be that the whole image is getting scaled slightly. If the browser window isn’t exactly the same size from one run to the next, the images in the UI will get scaled – perhaps by only a pixel in any dimension, but that would be enough to throw off the match. If you think that might be the case, you can have your script make sure that the window is always the same size by making sure the upper left corner of the browser window and the lower right corner are always the same distance apart. You can use the upper left corner location and do something like this:
drop imageLocation("UpperLeftImage") + (700, 500)
Again, if you don’t think either of these is the reason, we’ll need more information, especially sample images.
BTW, the forums are not a first tier support mechanism; they are intended as a community resource. As a customer with a paid support and maintenance contract, you should submit your issues via e-mail for priority handling.