Repeated Pop Up requesting Network User

[Rhonda]

Since migrating to Office 2000, whenever outlook is open,
there is a pop up that appears periodically asking for
network password. All email accounts are operating
correctly. This pop-up is not disabled and has to be
canceled mulitple times throughout the day.

Any suggestions for how I can get rid of it would be
appreciated. I have downloaded all the updates; none of
them have corrected the problem.

Thanks.

Rhonda