Hello Booker,
It seems like this has something to do with permisions or something.
Are you the 'Administrator' of your computer?
So no limited user account?
Also, some firewalls and/or Anti-Virus software can block registry changes attempts.
Try to disable those programs when trying to cleanup the registry and enable it afterwards.
Or.. check if you can add PowerTools to some kind of exclude list.
Let us know if something worked :).