Can't send or receive mail in Outlook 2003

I installed Office Professional 2003 with no problems
onto Windows Professional. I had previously used Outlook
Express and after setting up Outlook 2003 I migrated all
of my settings, email and contacts into Outlook 2003 with
no problems. However I can't send or receive email via
Outlook and when I try I get a dialogue box that
says: "The operation failed. An object could not be
found". I also found that Microsoft Exchange won't sign
in.

I reviewed all of the settings in Outlook and found them
to be correct, but then I found that when I send a test
message via the Outlook set up page the message goes to
Outlook Express even though Outlook is selected as the
email client. I also found that I can still send and
receive email via Outlook Express even though it's not
selected at the email client.