Profile of Admin = page not found

I have a strange situation going on with a site I'm working on.

Using the user name to view their profile, which is the admin or first account also know as 

http://mysite.com/admin or http://mysite.com/1 both are the same profile. I know seasoned members know this but a lot do not.

http://mysite.com/admin results in a "page not found" while,

http://mysite.com/1 reveals the profile for the admin or first member, this is the only profile as well that is doing this.

Any suggestions?

Did you look in the database table Profiles and see what is listed there for the Nick?  Perhaps something strange happened with the Nick.  Did you try changing the Nick for admin?

If the profile nickname of id=1 was changed then /admin will no longer work.

 No, I may do that.

 I need to ask the client if they did that which is most likely the case.

In response to that question about changing the id-1, I have not made any changes. "Page Not Found" is still the issue.

Did you try changing the name using admin as the new name?