By chance are you using Norton Internet Security 2006? There are some posts
for this already posted but not resolved.

"Peter" wrote:

I get an error message using Outlook Express 6 in Windows
XP when I click on Create New Message which says there
was an error openning this message. When i click the
address book i get "unable to open address book. Address
book may not be installed correctly" I can receive mail
but thats about all i can do. Worked fine until the
other day. Seems like something is corrupted. How do
you go about repairing, reinstalling Outlook Express 6?