I can't install itunes update registry permission

I see others with the same issue but no working solution. this is the key named in the error message box... HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Interface\{915DA835-02FE-4953-92FA-624BDF5D85AB}\ProxyStubClsid
The error says I don't have permission.
I have tried to change the permission but it still doesn't change.
I have run a couple registry cleaning programs Regfix and Regcure no change.
I have spoken to Apple they had me go through and remove everything with windows install clean and folders, etc. No luck still the same error. I can't copy the box for you unless you can direct me how to get a screen print on here.
I called Toshiba they had me do alot of the same stuff and then said I need to erase and reinstall software that came with the laptop.
Any help is greatly appreciated.