This is bizarre, but it's happened to me several times from two separate computers using Quark 9. When I go through the Save dialog to save a file, at times Quark will paste whatever happens to currently be in the clipboard into the Quark file just before it saves. This has happened both when doing a "Save As" procedure and when doing a Print/PDF/Save-as-postscript-file process. Obviously this is pretty inconvenient when it happens. Eg, if I happen to have a text box active when I hit Command-Shift-S, it will paste a piece of text or inline graphic into the text box (depending on what's in the clipboard at the moment). If there's an object in the clipboard it can paste it onto the page regardless of whether you're in a text box or not.
This is one more strange bug that can destroy my page at the worst possible moment, that I have to watch for every time I work, now. Has this happened to anyone else? (Or have random things appeared in your saved documents or PDFs that you swear you never put there?) If so, is there a fix?