AS AN ADMINISTRATOR: When you view Content pages and others clicking the back button generates an open page (checked out) you must either select and click the Close, Apply or Save button located in the top right above the Editing selections.
Once you do this the page becomes LOCKED and must be checked back in .To check in all locked pages goto Administrator, Main Menu>System>Global Check In and click to open, once opened all the checked out items will be checked back in. You can then continue working.