While there are many causes of this behavior,mine had to do with bad RAM.
I setup a new workstation on Friday, but over the weekend, after two Microsoft updates (KB920872, KB900485), outlook started shutting unexpectedly. Troubleshot, uninstalled office and tried reinstalling, kept saying that the files on the DVD-Rom drive were corrupt. Swapped cables, swapped drives, swapped IDE channels, no luck, same result. Tried reinstalling Windows XP Pro, with no luck, same corrupt files message.
Swapped RAM and it finally took the XP Installation. Installed Office XP and Outlook 2003 no problem. Works now.