Windows 7 ultimate reactivation problem

Hi,
I cannot reactivate Windows 7 ultimate, after hardware problems. I reinstalled on clean hard drive and now it keeps telling me that it is being blocked. Then I contacted Microsoft & they suggested me to follow some steps. I tried what they suggested in the run dialog, but does not work.
Keeps saying:
Error:0XC004F025 Access denied; the requested action requires elevated privileges.
Please help me!
