When TOAD is first opened after a new install, by opening the Editor, the Navigator window also opens. As a rule, I click the X in the upper right-hand corner of the navigator, and remove it from view. In this case I cannot get the Navigator window to remain hidden. Every time I open a new Editor window, the Navigator appears, and has to be closed or unpinned.
Check the "Auto-save current desktop" option, which can be found by selecting View | Toad Options | Toolbars/Menus - Toolbars.