URLs of other people's profiles show "/my-profile/[permalink]

Hi guys, another one for you: For some reason, the urls of other users' profiles end defaulting to the user's own profile... here's what I mean.

My intention is to send UserA, via email, the url of UserB, and I want the URL to look like this:

http://mysite.com/UserB-permalink

This works. However, as soon as you click on one of the profile menu items (like About, or Basic Information), the URL flips to

http://mysite.com/my-profile/UserB-permalink

... where /my-profile is the path the menu item I have defined so that UserA can quickly reach his/her profile.

I suspect this is my configuration error... Can you help? I've been spinning on this for hours!

Thanks in advance.