The latest documents on which you have worked are listed in the Start menu, My Recent Documents. This list is kept from one session to another. If you use a workstation accessible by multiple users, you can ensure that this list be purged when you close Windows.

Right click on Start and select Properties. Then click Customize and select the Advanced tab. Then uncheck the box “show recently opened documents.” Note that the button on the right allows you to immediately erase the list.