Outlook will work in Win2K, not XP

[Chris]

Background:
NT4 Based Network
Roaming Profiles

I have a user who when she logs onto her Win2K machine,
everything works fine.
When she goes to an XP machine, she cannot run outlook.
A dialog box pops up asking her for her username, pass and
domain. When the proper information is entered, she does
not have any success.

Has anyone ever seen and solved this?

My next step is to blow away the profile...but I would
rather "fix" the problem.

Thanks,
Chris