Here's another,
http://spike.wharton.upenn.edu/suppo...blackberry.cfm, which mentions choosing profiles.
I think you are seeing the prompt because Outlook has the multiple profies setup (however you did it in first place).
I guess I never saw it because I only have one Outlook profile in my windows log in, and other users always log in with a different windows profile.
I guess you have two choices. Figure out which profile is the one you have been using, and choose that, or create a new profile and figure out how to get your existing data into the new profile. Maybe somebody has a better idea.