This was the behavior I was seeing that I mentioned in another post. I would clone a checkbox group or a listbox group and save it. It would return to the form but the new option was not there. I tried it several times. After cloning, I also noticed that when I clicked on any of the question options, it would immediately drop back to the form. When I finally scrolled down the form page a bit, that's when I saw the GUID error. (A critical error has occurred. GUID should contain 32 digits with 4 dashes (......).
I'll bet if you scroll down after submitting your newly cloned item, you'll see the same error. I happened to have been working on the module in an upper level pane, but the error is posted into the 'content pane'.