Outlook 2003 and Outlook Express both close immediately

[D J Folds]

I developed a problem with Outlook 2000 in which the
program exited immediately when trying to start it. I
was ready to move to Office 2003 anyway, so I bought a
copy and installed it. All the other Office applications
run fine, but Outlook 2003 closes immediately just as
Outlook 2000 did. I tried switching to Outlook Express
just to get email access, but it also closes immediately.
I suspect a registry problem, but don't know what to look
for. An ideas?