wrong items appearing in navigation pane

There was a time in recent memory (yesterday) when only my calendars appeared
in the My Calendars navigation task pane. Now suddenly, I'm living in a mixed
up world, and I honestly don't know what I clicked to make it that way. The
wrong items/folders are appearing in the wrong navigation panes:

- contacts AND calendars are appearing under My Calendars
- notes, tasks AND contacts are appearing under My Contacts
- tasks, contacts, more tasks AND calendars are appearing under My Tasks
- miraculously, only mail folders appear in the All Mail Folders pane

I have looked through the Microsoft knowledgebase and can find no reference
to how this is done (or corrected, for that matter). I want ONLY calendar
items appearing in My Calendars -- the way it used to be!

Anyone know what controls this and how I can restore the "default" view to
the navigation pane?