How To Enable Registry

I am using Windows XP Pro SP2 and I had to install a new program for my work as a Software Engineer.  While doing the set up I am suppose to type "regedit" in the "run" box to make it work.  When this is typed and I click on OK - I get an error message saying "Registry editing has been disabled by your administrator."  However, according to my computer - I am the administrator.  I am also try in administrator login but same problem coming. i am also trying by many ways but still problem is same.
Guys help me out!!!