Ever since 4.0 there is a MenuSuite "feature" that has really annoyed me. If you open a form from one menu pane, then click on a new menu pane, then close the form, you jump to the original menu pane.
Beneath all of the MenuSuite buttons, to the left of the little arrows, right click the mouse.
Select Navigation Pane options.
uncheck Track open windows.
And your life will be whole again