go to pages and menus on the admin panel add new page in main menu catergory name the page my profile and select external adress enter http://www.your-domain.com/my-profile thats it
I can acess that url normally, but from the menu iten it does not show it.
I tested this out on my site and got the same result. Although the url was identical I got a blank page as well. I think one of the staffers may have to chime in on this one.
*******Edit
Nevermind on that. I just got it to work. Instead of using an internal page select the external option and use the full url to the profile.