Stuart, you've got your problem sorted out now but I thought I would make a suggestion. Make a keyboard shortcut for Edit>Delete Guides. This will make it easy to clean up your model from time to time. Depending upon what I am working, I might use a lot of guides. The model can get quite cluttered so the keyboard shortcut gives me a quick, one button clean up. To set the shortcut go to Window>preferences>Shortcuts. In the Filter box type "Guides" You should actually see Edit/Delete Guides as you type the 'u'. Then click in the Add Shortcut box to the right of the Function list, type your shortcut and hit the '+' button Hit OK and you're good to go.