Front End Menus have unexpectedly changed

Symptom

The Front End Menus have changed, but no-one has changed the site Menu.

Cause

The mostly likely cause of this is that when the Menu Editor has been used for other sites, all the boxes (Sandpit, Prelive, Live) were ticked. This is usually due to a misunderstanding that only the changes will go into the other sites. In fact ticking the boxes means that the whole Menu structure is copied to the other sites; this is intentional, for example, to allow design of the menu structure in the Sandpit and then copy it into Prelive and Live.

Solution

Make all User Administrators aware of this aspect of the use of the Menu Editor.