Username/password error on my account only

I administer an Exchange2003 environment and wanted to also allow POP3
access, so I enabled that on the server. Now, I can set up any other users
to receive their email via POP3 in Outlook Express with no problems - they
get it just fine. But on my account only, (all settings exactly the same as
the others, even on the same computer), I keep getting:

There was a problem logging onto your mail server. Your Password was
rejected. Account: (My Account), Server: 'exchange.(mydomain).com',
Protocol: POP3, Server Response: '-ERR Logon failu unknown user name or
bad password.', Port: 110, Secure(SSL): No, Server Error: 0x800CCC90, Error
Number: 0x800CCC92

I've double checked all my settings on both the server and client end, (full
domain admin rights), and can find nothing different than the other users.
Any ideas on what else to check? Anti-Virus makes no difference.

Thanks for any suggestions.

John