Master slides Randomly Changing

Hey Walt, please excuse my ignorance if I've not interpreted your response correctly. When you say that a storyline file is not a saved file, but rather is a series of zipped, saved files, are you referring to a module that has been exported ready to publish? I am referring to opening a singular .story file.   Just to ensure we're both on the same page, I can save a project as a .story file and create and export of files via publish and the eLearn course behaves as expected. As an example, I might re-open the .story file a week later, and it opens as expected in the previous saved state. Let's say, for example, that the project contains 30 slides. I might go in and make a small edit to a line of text on slide 28. Before I re-save the the .story file to reflect the changes I've made, or, re-publish to export the course files, I notice that despite not having made any changes to slide 5, the layout has automatically changed. I have started to become more observant with this lately, but it seems to be that making an edit on one slide can cause the layout on a random slide also contained within the course to also change. On the last project, this was the exact nature of the problem I observed. I re-opened a saved .story file, checked the layout was ok, made a small change, re-checked the layout and observed a random slide had changed. Easy to work through with small modules, but a little more frustrating when working on a larger eLearn to have to go back and check the slide layout for all slides when only making edits to one page prior to re-saving to ensure the bug hasn't cropped up again.