Iwould add that I saved the active glass image as a png, not a bmp, if it matters.
I also tried just making a new image and saving it as your image which also became corrupted, so I am guessing the code in relation to the skin got screwy and needed deleted and replaced. So do the above fix, delete code, delete image from file, make new, import and save, should fix it.
I also deleted all 4 images and replaced with the new, fyi.Active-inactive-activeglass-inactiveglass.