Outlook 2010 has a nifty feature in the status bar: view buttons. This is especially useful on netbooks and laptops with small screens to quickly show more of the reading area. Each folder type has at least two buttons: one to set the navigation pane, to-do bar, and ribbon to open (Normal view) and one button to minimize those elements, giving you more room to read your mail or view calendar or contacts.
These buttons are preprogrammed for "set to-do, navigation pane, and ribbon to Normal view", not "restore my previous settings". They create a view that matches the icon: open all the panes or minimize them to allow more reading space.
If you prefer a specific layout, such as the navigation pane always minimized or the to-do bar turned off, don't use the buttons, use the minimize/expand button on the other features or the keyboard shortcuts to show or hide the panes. You can hide the buttons but right clicking on the status bar and removing the check from View shortcuts.
Alt+F1: Navigation pane (off, open, minimize)
Alt+F2: To-do bar (off, open, minimize)
Ctrl+F1: Ribbon (open, minimize) Can also double click on a tab to minimize or open the ribbon.
Note the several of the other status bar items are clickable: Reminders will show the reminder window, when Outlook is checking for mail, the Send/Receive button opens the Show progress dialog, the zoom % opens the Zoom dialog, and the Quota button opens the File tab.