Outlook XP (2002) startup error: "...requires Microsoft Outlook Express 4.01 or greater."

[cgladish]

On a system running WinXP Pro w/ SP2 and Office XP. Attempts to open
Outlook result in the error message:

"Cannot start Microsoft Outlook. Outlook requires Microsoft Outlook
Express 4.01 or greater. You can install Outlook Express by running
IE5Setup.exe from the IE5 folder located on your CD or through Windows
Update website."


Outlook Express version 6 is installed and runs without error, though
it is not used. The version of Outlook installed is Outlook XP.

I have viewed and tried to follow the advice in several Microsoft
support articles, to no avail, including, but not limited to:

http://support.microsoft.com/kb/287683/EN-US/
http://support.microsoft.com/default.aspx?scid=kb;en-us;320863
http://support.microsoft.com/default.aspx?scid=kb;en-us;212991
http://support.microsoft.com/default.aspx?scid=kb;en-us;287683

.... amongst others.

All of these either are not do not solve the issue, or are not
applicable.

I have tried to run the IE5setup from the Office XP CD, but am not
allowed to, as I already have IE6 installed. Outlook Express opens
without problem. I have tried using Add/Remove Programs to re-install
and reregister the OE componenst, but the problem persists. I have run
Windows Update, just to make sure I am not missing anything, and
everything's up to date. I have also uninstalled and reinstalled the
Office suite, but the problem persists. I believe I have exhausted the
suggestions presented by MS's support site.
Does anyone else have any more suggestions?