[Andrew]

Sounds like that document has auto-layout turned on. I'm going to guess that when you created your document you used one of the templates that defaults to auto-layout (many of them do). You can disable it by going to the Canvas: Diagram Layout inspector and unchecking the "Automatic layout" checkbox. (And in general, if you email our support team via the Send Feedback item in the Help menu, you should get a pretty timely response.)