Your mailbox has been temporarily moved ...

I made a remote connection to a client's pc (Win XP Pro) and uninstalled MS
Office 2003 Standard, and then installed MS Office 2007 Pro Plus from a
install point on a server (MS Server Standard 2003 SP2). The uninstall and
install seemed to go fine.

But when I opened the client's Outlook 2007, I get the following message:

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Your mailbox has been temporarily moved on Microsoft Exchange server. A
temporary mailbox sists, but might not have all of your previous data.

You can connect to the temporary mailbox or work offline with all of your
old data. If you choose to work with your old data, you cannot send or
receive e-mail messages.
[Use Temporary Mailbox] [Use Old Data] [Cancel]

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The Exchange Server is 2003 SP2, running on Windows 2003 Standard SP2. The
client is running 1 additional smtp email alias.

I have tried turning off cacheing and restarting Outlook -- turning back on
cacheing and restarting outlook. It didn't help.

Any ideas?