Just a recap. Admin is not God.
by R. Proffitt - 1/20/13 9:15 AM
As long as you think you have all rights, you may be stumped and won't look into the usual. Let's get past the "I'm the only user/admin" and remember that even the admin must obey NTFS permissions.
And you would try a new Admin account. And again the old lesson of the single account can not be forgotten. Keep an admin spare account.
Sorry that I can't guess which permission is off but we must get past the single user/admin hurdle before we can continue as well as getting our spare admin account in place.