Loss of Administrator Account?

I am runnning Windows XP Pro on my home machine, and somehow the Administrator account has disappeared. I have no way (that I know of) of logging in as Administrator, but I do have an account with Administrator rights. When I try creating a new user named Administrator, it says that the user name already exists. I have no idea how to go about restoring the Administrator account so that I might be able to log in under that name. Any help would be greatly appreciated. Thanks in advance.