Since posting my last msg, I've noticed that Outlook exits when I click on the 'Show Desktop' icon that's on the far left (Quick Launch area) of my System Tray.

I used Notepad to open the Show Desktop.scf file, and here's the (command lines?) that .scf file contains:

[Shell]
Command=2
IconFile=explorer.exe,3
[Taskbar]
Command=ToggleDesktop

(exactly what's on http://support.microsoft.com/?kbid=190355 )

There definitely seems to be a connection between Outlook exiting unecessarily and whatever the system does to Show Desktop.

Hope this info helps us solve this!!!!