2000 to 2003 network password pop up

[Jim]

I recently converted to Outlook 2003 from 2000 and when I
select send/receive I get a pop up asking for a password
for a provider I had last year. The whole process stops
until I select cancel. If I try the "old" password I get
an error message. By selecting cancel the operation is
completed successfully.
Can someone tell me how to delete this pop up option?
Tks in advance
Jim